Military rule in Thailand is likely to last longer than expected and has been more repressive than after the country's last coup in 2006, a senior US official says.
The official told a congressional hearing Washington was still looking at whether the big regional Cobra Gold military exercise held annually in Thailand could go ahead there next year given the military takeover in May.
''Initially, we held out hope that - as happened with the 2006 coup - the military would move relatively quickly to transfer power to a civilian government and move towards free and fair elections,'' said Scot Marciel, the US principal deputy assistant secretary of state for East Asia.
''However, recent events have shown that the current military coup is both more repressive and likely to last longer than the last one,'' he added.
Marciel said in testimony to the Asia-Pacific subcommittee of the House Foreign Affairs Committee that the coup had put the United States in a difficult position, given that Thailand is a key US ally in Asia.
''The challenge facing the United States is to make clear our support for a rapid return to democracy and fundamental freedoms, while also working to ensure we are able to maintain and strengthen this important friendship and our security alliance over the long term,'' he said.
Marciel said Washington hoped that strong international criticism of the military takeover would lead to an easing of repression and an early return to democracy. He said the United States would continue to urge for the martial law to be lifted and elections to be held sooner than a vague 15-month timeline laid out by the military government.
However, he added: ''To be honest, it's very hard to predict how long they are going to stay in power.''
Until there is a return to elected government, ''we will not be able to do business as usual,'' Marciel said.
As required by US law, Washington has frozen US$4.7 million (NZ$5.3m) of security-related assistance since the coup and canceled high-level engagements, some military exercises and training programs for the military and police.
Marciel said Washington had yet to make a decision on the Cobra Gold exercises planned for early next year in Thailand, which he called ''hugely important ... not only for Thailand and the United States, but for the region.''
''It's something we're looking at. We have a little bit of time to work with.''
Steve Chabot, chairman of the subcommittee at which Marciel spoke, suggested that Cobra Gold could be moved to another country, such as Australia, and added: ''It could clearly send the wrong message if we allowed (Thailand) to participate.''
Washington has also yet to decide whether Thailand would receive a presidential waiver on sanctions - including withdrawal of US support at the International Monetary Fund and the World Bank - that could be imposed for its failure to deal with human trafficking, Marciel said.