VA now presumes Agent Orange exposure for veterans who served at any U.S. or Royal Thai military base in Thailand from Jan. 9, 1962, through June 30, 1976. The PACT Act removed the old requirement to prove perimeter duties or a qualifying military job. Veterans still need evidence of their service dates, base assignment, and current disability.
- The PACT Act changed the Thailand exposure rule. Veterans no longer need to show that they worked near a base perimeter or held a security-related job.
- The current eligibility window runs from Jan. 9, 1962, through June 30, 1976. Service at any U.S. or Royal Thai military base during that period may establish presumed herbicide exposure.
- The old seven-base list the VA used for presumptive locations is no longer a closed list. It remains historically important, but the current law covers other qualifying bases, including Nam Phong.
- A prior perimeter-based denial is worth appealing. The new presumption can address the exposure element, but it does not automatically restore every earlier effective date.
- Presumptive conditions and direct claims follow different rules. A recognized Agent Orange condition generally does not require a separate nexus once exposure is established. A condition outside the presumptive list usually does.
When and How Was Agent Orange Used in Thailand?
Historical records document herbicide use inside Thai military-base perimeters during the Vietnam War, but they do not show that spraying occurred continuously from 1962 through 1976.
A 1973 Department of Defense report known as the Project CHECO report discussed the security role of herbicides insideThai base perimeters, which VA interpreted as being on or near the perimeter of the bases. The report did not consistently identify the exact herbicide formulation used at each location, but that distinction no longer controls most current claims.
The presumptive service window for VA claims is Jan. 9, 1962, through June 30, 1976. A veteran who served at any U.S. or Royal Thai military base during that period qualifies for presumed herbicide exposure.
Does It Matter If a Veteran Did Not Serve During a Documented Spraying Operation?
A veteran who meets the PACT Act’s base-and-date requirements does not need to identify the specific spray operation, chemical mixture, or perimeter where the exposure occurred.
The current presumption applies based on qualifying service at a covered U.S. or Royal Thai base during the statutory window. VA should not require proof that a veteran personally saw spraying, handled drums, or worked where vegetation was cleared.
Veterans still need evidence showing:
- The base where they served
- Service dates in Thailand
- A current diagnosed condition
- Whether the condition qualifies for presumptive or direct service connection
What Was the Old Thailand Perimeter Rule?
Before the PACT Act, VA generally conceded herbicide exposure only when the veteran served near the perimeter of one of seven named Royal Thai Air Force bases. The strongest cases often involved:
- Security police
- Security patrol dog handlers
- Members of security police squadrons
- Veterans whose jobs or daily duties placed them near the fence line
Other veterans had to prove perimeter proximity through base maps, photographs, performance reports, buddy statements, or descriptions of their work and living areas.
The perimeter rule caused many cooks, clerks, mechanics, supply personnel, medical staff, and other support workers to receive denials even though they served at the same installations. Since the PACT Act removed the job and perimeter requirements, previously denied veterans can now qualify for the presumption.
Does the Old Perimeter Evidence Still Matter?
It can. A veteran filing a current claim usually does not need perimeter evidence to establish exposure. However, that evidence may still matter when the veteran seeks an effective date tied to an earlier claim filed before the PACT Act.
An earlier effective date is not automatic. It may depend on whether:
- The earlier claim or appeal remained pending
- The veteran continuously pursued the decision
- The evidence already established exposure under the former perimeter framework
- VA made a legal or factual error in the earlier decision
- Another effective-date rule applies
Do not assume that the PACT Act automatically restores benefits to the date of every prior denial.
Thailand Military Bases with Agent Orange Exposure
The PACT Act covers any U.S. or Royal Thai military base in Thailand during the qualifying period. Historically, most U.S. veterans served at the following locations during the Vietnam War.
Udorn Royal Thai Air Force Base
Udorn, also called Udon Thani, sat in northern Thailand and became one of the busiest U.S. air installations in the country. The base supported reconnaissance, fighter, intelligence, and other air operations tied to missions over Laos, North Vietnam, and the surrounding region.
U.S. Air Force units began arriving at Udorn in the 1960s. The base later served as headquarters for major reconnaissance operations, including photo reconnaissance and F-4 missions.
Its high operational tempo meant that maintenance crews, security personnel, communications workers, supply staff, administrative personnel, and other support workers moved through areas connected to flight line and base defense activity.
Under the old VA policy, an Udorn veteran often had to prove that their work, housing, or regular duties placed them near the perimeter. Under the PACT Act, the focus is now simpler: whether the veteran served at Udorn during the qualifying Thailand window and has a current condition connected to herbicide exposure.
U-Tapao Royal Thai Air Force Base
U-Tapao, on the Gulf of Thailand, became the largest U.S. air base in Thailand and a major launch point for B-52 bombing missions during the Vietnam War. It also supported KC-135 tanker operations, aircraft maintenance, logistics, and other large-scale air operations.
Many veterans who served there did not have security-related military jobs. They may have worked in maintenance, transportation, communications, medical support, administration, supply, food service, or other roles that VA previously treated as harder to prove under the perimeter rule. Now they no longer have to prove that they stood at the fence line or worked in a specific perimeter job to establish presumed exposure. Service records showing assignment to U-Tapao during the PACT Act window should satisfy the exposure element.
Takhli Royal Thai Air Force Base
Takhli, in central Thailand, supported major tactical fighter operations during the Vietnam War. The base housed F-105 Thunderchief operations and other combat-air missions connected to the air campaign over North Vietnam.
Because Takhli operated as a busy combat airfield, many veterans served there in jobs that supported flight operations rather than perimeter security. Pilots, ground crews, weapons personnel, mechanics, fuel specialists, transportation workers, clerks, and other support personnel may all have records showing service at Takhli.
Before the PACT Act, many Takhli veterans needed evidence that their duties took them near the base perimeter. Current law removes that extra burden for qualifying service dates. However, a veteran still needs records showing service at Takhli and medical evidence showing a current diagnosed condition.
Nakhon Phanom Royal Thai Air Force Base
Nakhon Phanom, or NKP, sat near the Mekong River across from Laos. The base supported special operations, rescue missions, gunship operations, intelligence work, and missions connected to the air war over Laos and the Ho Chi Minh Trail.
NKP’s location made base defense a major concern. Under the former VA policy, that history often helped veterans who could show perimeter duties or regular work near the fence line. Security personnel, aircraft maintenance workers, communications personnel, transportation workers, and other support staff often looked for unit records, maps, and buddy statements to prove where they worked.
Since the PACT Act, the key evidence for most current NKP claims is service at NKP during the qualifying period, a current diagnosis, and whether the condition is presumptive or needs a direct medical nexus.
Korat Royal Thai Air Force Base
Korat was one of the largest and most active U.S. fighter bases in Thailand. It supported F-105 and F-4 operations, reconnaissance work, electronic warfare activity, and air defense missions during the Vietnam War.
Many Korat veterans worked in roles that kept the base running rather than in jobs VA once viewed as perimeter-related. Weapons mechanics, aircraft mechanics, fuel handlers, communications workers, medical staff, administrative personnel, security forces, and supply personnel all may have service records tying them to Korat.
Under the current Thailand presumption, VA should not deny exposure solely because a Korat veteran was not security police or did not document daily work at the perimeter. The veteran’s base assignment, dates of service, and medical diagnosis remain the core pieces of evidence.
Ubon Royal Thai Air Force Base
Ubon, in eastern Thailand, supported fighter, gunship, reconnaissance, and other combat-air missions. The base hosted major F-4 Phantom operations and sustained heavy flight-line activity during the Vietnam War.
Ubon veterans may have served in aircraft maintenance, weapons loading, transportation, communications, medical support, administration, supply, food service, security, or other base-support roles.
Under the old rule, Ubon veterans often used maps, photographs, performance reports, and lay statements to show that their work or living areas were near the perimeter. That is no longer required for the exposure presumption if the veteran served at Ubon during the statutory window. However, old perimeter evidence may still matter if the veteran seeks an earlier effective date tied to a pre-PACT Act denial.
Don Muang Royal Thai Air Force Base
Don Muang, near Bangkok, served as a command, transportation, airlift, refueling, and logistics hub. Veterans stationed at Don Muang could have supported airlift operations, tanker activity, command functions, communications, administration, transportation, or logistics.
Some veterans were denied under the old framework because Don Muang service did not always fit the narrow perimeter-duty evidence VA expected. Because the PACT Act does not distinguish between combat bases and support installations, qualifying service at Don Muang during the statutory Thailand window establishes presumed exposure on the same legal basis as service at the larger fighter and bomber bases.
Nam Phong, the “Rose Garden”
Nam Phong, known to Marines as the “Rose Garden,” was a Royal Thai base used by U.S. Marine Corps aviation units during the Vietnam War. Marine Aircraft Group 15 operated from Nam Phong beginning in 1972, after the Easter Offensive increased the need for Thailand-based tactical aircraft.
Nam Phong was not one of VA’s former seven named Royal Thai Air Force bases. That exclusion caused confusion for Marines and other veterans who served there. Some were told that Nam Phong “didn’t count” because it did not appear on the old list.
The PACT Act resolved that problem for qualifying service dates. Veterans who served at Nam Phong can now win their claims by submitting records showing their assignment, dates in Thailand, unit, and duties.
For any of these locations, if the claim involves a condition outside the Agent Orange presumptive list, the veteran may also need a medical opinion connecting the condition to herbicide exposure or another service-connected disability.
What If My Base Is Not Listed?
A Thailand base does not have to appear on any list to be a recognized Agent Orange exposure location. You should be eligible for VA benefits if you can answer yes to these questions:
- Was it a U.S. or Royal Thai military base?
- Did you serve there between Jan. 9, 1962, and June 30, 1976?
- Can your personnel or unit records verify that service?
What Conditions Are Granted VA Disability?
Once VA establishes qualifying Thailand service, the same Agent Orange disease presumptions available to other exposed veterans apply. For presumptive conditions, VA generally does not require a separate medical opinion proving that the herbicide caused the condition.
Hill & Ponton analyzed Board of Veterans’ Appeals decisions involving Thailand herbicide appeals from 2021 through 2025 and found that grant rates varied substantially.
| Disability issue | Total | Granted | Remanded | Denied | Other / Mixed |
|---|---|---|---|---|---|
| Diabetes | 1,483 | 1,125 (75.9%) | 185 (12.5%) | 165 (11.1%) | 8 (0.5%) |
| Arteriosclerotic heart disease / CAD / IHD | 929 | 728 (78.4%) | 99 (10.7%) | 100 (10.8%) | 2 (0.2%) |
| Hypertension | 615 | 379 (61.6%) | 138 (22.4%) | 93 (15.1%) | 5 (0.8%) |
| Prostate cancer | 508 | 420 (82.7%) | 32 (6.3%) | 54 (10.6%) | 2 (0.4%) |
| Peripheral nerve disorders | 347 | 152 (43.8%) | 99 (28.5%) | 94 (27.1%) | 2 (0.6%) |
| Parkinson’s disease | 208 | 164 (78.8%) | 26 (12.5%) | 18 (8.7%) | 0 (0.0%) |
| Kidney cancer | 162 | 96 (59.3%) | 38 (23.5%) | 26 (16.0%) | 2 (1.2%) |
| Respiratory cancers | 101 | 79 (78.2%) | 13 (12.9%) | 9 (8.9%) | 0 (0.0%) |
| Bladder neoplasm | 84 | 68 (81.0%) | 8 (9.5%) | 6 (7.1%) | 2 (2.4%) |
| Leukemia | 75 | 62 (82.7%) | 7 (9.3%) | 6 (8.0%) | 0 (0.0%) |
| Hypothyroidism | 70 | 50 (71.4%) | 11 (15.7%) | 9 (12.9%) | 0 (0.0%) |
Source: Hill & Ponton analysis of Board of Veterans’ Appeals decisions involving Thailand herbicide claims, 2021 through 2025.
What If the Condition Claimed Is Not Presumptive?
A condition outside the Agent Orange presumptive list may still qualify through direct service connection. Under Combee v. Brown, the absence of a presumption does not prevent a veteran from proving actual causation.
A direct claim generally requires:
- A current diagnosed condition
- Qualifying herbicide exposure or another in-service event
- A medical nexus connecting the condition to service
The medical opinion should explain why the condition is at least as likely as not related to the veteran’s exposure. It should address the veteran’s records, medical history, risk factors, and relevant scientific evidence.
A veteran may also pursue secondary service connection when an established service-connected condition caused or aggravated another disability.
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What Evidence Do You Need for a Thailand Agent Orange Claim?
The PACT Act made the exposure element easier, but VA still needs evidence showing where and when you served.
Service Records Showing Your Base and Dates
- DD-214
- Official Military Personnel File
- Assignment orders
- Performance evaluations
- Temporary-duty orders
- Travel vouchers
- Pay records
- Unit histories
- Flight or maintenance records
- Awards and citations
- Service treatment records
A DD-214 may show Thailand service without naming the exact base. Personnel records, evaluations, or orders may provide the missing detail.
Medical Records Showing a Current Diagnosis
- VA treatment records
- Private medical records
- Diagnostic testing
- Specialist reports
- Pathology records
- Surgical reports
- Medication history
The diagnosis must match the condition claimed. If VA disputes whether the disability qualifies as a presumptive condition, a specialist’s report may help clarify it.
Evidence From the Earlier Claim
If VA previously denied your claim, obtain the decision letter and identify the exact reason. You may also need:
- The prior C&P examination
- VA’s military-records research
- Submitted base maps or photographs
- Lay and buddy statements
- Prior personnel records
- Earlier medical opinions
This evidence helps determine whether the new presumption resolves the denial or whether another issue remains.
Perimeter Evidence for an Earlier Effective Date
You generally do not need perimeter evidence for a current PACT Act claim. However, it may support an earlier effective date argument if it shows that VA should have conceded exposure under the rules and evidence available when the earlier claim was pending.
Examples of perimeter evidence:
- Base maps
- Photographs
- Performance evaluations
- Barracks or work-area locations
- Duty descriptions
- Security or patrol records
- Buddy statements
- Personal statements describing regular perimeter contact
The evidence should explain where you worked, lived, traveled, or performed recreation in relation to the perimeter.
Nexus Evidence for a Non-Presumptive Condition
If the condition is not presumptive, obtain a medical opinion explaining the connection to herbicide exposure or another service-connected disability.
The physician should not rely only on the veteran’s diagnosis and general Agent Orange research. The opinion must apply the evidence to the veteran’s individual medical history.
Why Does VA Deny Thailand Agent Orange Claims?
Many Thailand claims still receive denials because VA applies an outdated rule, cannot verify the base or dates, or finds that the claimed condition is not presumptive. These claims usually require a strong direct or secondary service-connection theory because proving Thailand exposure alone does not establish the medical connection.
VA Says the Job Was Not Near the Perimeter
Respond by pointing to the current presumption for service at any U.S. or Royal Thai military base during the statutory period. A veteran’s job and location on the base should not control exposure under the PACT Act.
VA Says the Thailand Base Was Not on the Old List
The former policy focused on seven Royal Thai Air Force bases. The current statute does not. Submit records establishing that you served at a U.S. or Royal Thai military base within the covered dates. Nam Phong and other qualifying installations are not excluded simply because they were absent from the old list.
VA Cannot Verify Presence at a Thailand Base
DD-214 may show overseas service without naming the installation. Submit personnel records, assignment orders, performance reports, travel documents, unit histories, or other records identifying the base.
VA Says Service Dates Do Not Qualify
The current window is Jan. 9, 1962, through June 30, 1976. Compare the complete personnel file with VA’s dates. Make sure VA considered temporary duty assignments, arrival and departure records, and corrected service documents.
VA Says the Condition Is Not Presumptive
The PACT Act’s location presumption does not make every medical condition presumptive. Determine whether the condition can be claimed through direct service connection or as secondary to another service-connected disability. A reasoned medical opinion may be required.
VA Granted Service Connection but Used the Wrong Effective Date
A PACT Act award does not automatically guarantee benefits back to the date of an older denied claim. Review whether the earlier claim remained pending, whether you continuously pursued it, and whether the earlier evidence established perimeter exposure under the rules that applied at the time.
Which Appeal Lane Should You Use?
- Supplemental Claim: For new and relevant evidence or when you need VA to reconsider an earlier denial under the current law.
- Higher-Level Review: For correcting an error, if VA applied the wrong law or overlooked evidence already in the record.
- Board Appeal: When the claim involves a disputed effective date, credibility finding, complex exposure history, or another unresolved legal or factual issue.
Get Help with a Denied Thailand Agent Orange Claim
The outcome of Agent Orange appeals often depends on whether VA applied the current PACT Act rule, verified the correct base and dates, and recognized the claimed condition.
Hill & Ponton is uniquely focused on assisting veterans in appealing denied VA disability claims. Our VA-accredited lawyers win 96% of the cases we take on, and we collect no fee until we win. If you were wrongly denied by the VA, request a free case evaluation to talk about your case and choose the best path to success.
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