Insisting the US was "deeply engaged" abroad, the Secretary of State, Mr Colin Powell, yesterday in Hanoi strongly denied charges that the Bush administration wanted to go it alone in the world.
Mr Powell's strong defence of President George Bush's policy came as he spent two days at an Asian regional forum in the Vietnamese capital and during a five-nation regional tour.
It also followed the administration's recent decisions not to ratify or join several international treaties and pacts, including a draft protocol on implementing a germ-warfare treaty.
"I think over time people will see that we are not unilateralists, we are deeply engaged," Mr Powell said.
"I mean, for the last 2 1/2 days I have been anything but a unilateralist here.
"The President's trip to Genoa [for the G8 summit last week] and the President's earlier trip to Europe, I think were important indications that we plan to be active members of the alliances and associations that we were part of," Mr Powell said.
But he conceded that the US might feel the need to pull out of some multinational conventions. "From time to time, one comes along, or more come along, where we do not believe it serves our interest," he said.
"And that is the case with the protocol to the Biological Weapons Convention." He said it was clear that a 1995 draft protocol on enforcing the 1972 convention was unverifiable.
"We had to call it the way we saw it. It's not as if suddenly we jumped up and said we're out of here."
In recent months the Bush administration said it would not ratify the Kyoto treaty on climate change which it regards as "fatally flawed" and the administration's push for missile defence likely to clash with the Anti-Ballistic Missile Treaty.
Meanwhile a US-based academic expelled from China after being convicted of espionage arrived in the United States yesterday, the second US university scholar evicted from China before Mr Powell holds talks in Beijing this weekend.
President Bush was "encouraged" by China's decision to free the two scholars but saw "additional problems" with Beijing's human rights record, the White House said yesterday.
"Two have now been released, and the President is pleased to note that, [but] additional problems remain in our relations with China on the human rights front," the Bush spokesman, Mr Ari Fleischer, told reporters.
"The President will continue to directly raise those issues with Chinese officials," said Mr Fleischer, who noted that Mr Bush had discussed the matter with President Jiang Zemin in a July telephone call.
Ms Gao Zhan, a sociologist at American University in Washington DC, and Mr Qin Guangguang, a published author, were granted medical parole two days after being sentenced to 10 years' imprisonment on charges of spying for Taiwan, the Chinese Foreign Ministry said.
On her arrival at Detroit Ms Gao said she was thrilled to be back and anxious to see her young son.