Two ships full of marines and heavy equipment steaming toward Sri Lanka were diverted due to a reduced need for aid, officials said, and instead bolstered the US task force off western Sumatra, the area hardest-hit by last week's tsunami.
But the highly sensitive nature of the US relief mission in southern Asia was highlighted when a spokesman for Sri Lanka's rebels, the Tamil Tigers -- considered a terrorist organization by Washington -- said Tuesday that the troops were being sent as spies to help put down their insurgency.
US officials insisted that the diversion of two ships had nothing to do with the Tamil Tigers' allegations, and that rerouting the USS Bonhomme Richard and the USS Duluth followed the Sri Lankan government scaling down its request for help.
The ships will join the aircraft carrier USS Abraham Lincoln and its battlegroup off the Indonesian island of Sumatra, where navy helicopters have flown dozens of relief and evacuation missions.
The USS Mount Rushmore, carrying a smaller contingent of marines, will travel on to Sri Lanka alone. It was expected to cross the Indian Ocean by the weekend.
US Embassy spokesman Philip Frayne said the change of plans was "purely a function of allocating the right resources in the right place."
"The military presence is strictly for humanitarian purposes," Frayne said. "The military will be operating in the south of the country to clear rubble and rebuild infrastructure and help Sri Lankans to recover from the tragedy."
But a Tamil rebel leader claimed that American troops, and those from neighboring India, being sent to help in the relief effort might use the operation as a cover to spy on the rebels, handing over intelligence to the government to help it fight the insurgents.
"The attempt by the American and Indian troops to land in Sri Lanka ... is totally based on their political and military interests," Nallathamby Srikantha told Voice of Tigers radio, the official rebel mouthpiece.
"They may try to collect details to help the government crush the Tamil national struggle in a future conflict," Srikantha said.
"We have to think how America ... will use its troops here," he said.
The US and India both officially consider the Tamil Tigers, which control a large portion of Sri Lanka's north and east, to be a terrorist group.
Frayne said that the US troops had no intention of going to Tiger-controlled zones.
The area of operations in Sumatra's Aceh Province is also highly sensitive because of a long-standing insurgency there and severed military ties between Indonesia and the US following East Timor's violent separation from the Southeast Asian country in 1999.
Previously restricted to outsiders, the Indonesian government was quick to open Aceh after the tsunami because it needed the help, but the image of large numbers of marines pouring ashore would be politically sensitive in the predominantly Muslim nation.
Colonel Thomas Greenwood, commanding officer of the 15th Marine Expeditionary Unit aboard the Bonhomme Richard, said the marines were aware of the concerns.
"We don't want to offend anybody's sensitivities," he said. "The alleviation of suffering and the loss of human lives should trump politics. We want to be helpful without being bothersome."