The US has downgraded its safety rating of Thailand's aviation authority following earlier findings by the United Nation's International Civil Aviation Organization (ICAO).
The US Federal Aviation Administration (FAA) found that Thailand did not comply with ICAO's safety standards.
Thailand's aviation authority told the BBC it was still formulating its response to the findings.
But the national flag-carrier Thai Airways said it would not be affected.
However, aviation experts said the safety downgrade would affect Thai carriers working as the main operator with a US airline under a code-share agreement, as Thai Airways does in some cases.
They also said the FAA's move would have a significant impact on some of Thailand's carriers if Europe followed suit with safety downgrades.
The FAA said its downgrade of the Thai Department of Civil Aviation (DCA) from a 'Category 1' to a 'Category 2' rating meant that Thailand either lacked the laws or regulations necessary to oversee air carriers in line with minimum international standards - or that it was deficient in one or more areas.
The regulator said those areas could include technical expertise, trained personnel, record-keeping, or inspection procedures.
The downgrade means Thailand's carriers will not be allowed to establish new services to the US.
Bangkok-based lawyer and aviation expert Alan Polivnick said the FAA was one of the most prominent civil aviation authorities in the world and that many of its counterparts would have no alternative but to consider the outcome of its recent findings.
"The FAA's downgrade is significant - and unfortunate," he told the BBC. "The Thai government has tried very hard to meet the standards required."
He also explained that the direct impact of the downgrade may appear to be limited to only those airlines serving the US - but that Europe would most likely weigh in before the end of the year with rulings against individual airlines flying into the EU.
Aviation specialist Ellis Taylor of Flightglobal said a move by the European Aviation Safety Agency (EASA) against individual Thai airlines would have an impact on Thai Airways as well as Bangkok Airways.
"Should Europe turn around and place Thailand on its blacklist, that would have a much greater impact on Thai Airways, as it is quite reliant upon European traffic - and in turn so is much of the Thai tourism industry," Mr Taylor said.
"Bangkok Airways could also be affected, as it could jeopardise the interline relationships they have with European airlines, which it is reliant upon."
Individual airlines could be removed from that list, Mr Taylor explained, but said the process was "very opaque and essentially up to the European Commission's discretion."
Short term repercussions?
However Mr Taylor said the FAA's action would be unlikely to affect the Thai carriers in the short term.
"The US isn't really a large market for them nowadays," he said.
"It will prevent them from expanding their code-shares with US carriers, such as Star Alliance partner United Airlines, but this is a relatively small market for them," he added.
The FAA said it had been in ongoing talks with Thailand's government but that discussions had concluded at the end of October.
Thai Airways said it would experience no commercial or customer impact following the FAA's findings as it had stopped its operations to Los Angeles - its only US destination - on 25 October.
The carrier has had to cut several other international routes this year as it continues to lose money in what is an increasingly competitive regional aviation industry.
The flag carrier said it would continue to serve its customers through its code-share and interline partners to USA destinations.
ICAO is a United Nations specialised agency. Its safety program is designed to ensure global standards for aviation safety and the civil aviation bodies of its member states.