Hillary Clinton has made a landmark trip to East Timor following recent elections there - the first US secretary of state to do so since the country's independence in 2002.
Mrs Clinton said her visit was a sign of America's support for the country and its commitment to the region.
She also praised East Timor's progress and successful elections this year.
Mrs Clinton arrived in the capital Dili from China as part of an 11-day tour of six countries in Asia.
During her seven-hour visit, she met Prime Minister Xanana Gusmao and President Taur Matan Ruak.
She congratulated East Timor on "three sets of free and fair elections this year, and a peaceful transfer of power to a new president, government and parliament".
She said her visit signified "a clear, unmistakable message that the United States has been, is and will remain a resident Pacific power", but added US engagement with Asia was not about containing China.
"We happen to believe that Asia and the Pacific are big enough for many countries to participate in the activities of the region," AFP news agency quoted her as saying.
Her one-day visit has been seen as fostering the impoverished country's hopes of joining Asean.
East Timor applied to join Asean in March, but there has been concern that the country may still be too unstable to become part of the region bloc.
"It's put an enormous burden on Asean as a whole,'' a senior official travelling with Mrs Clinton told AFP. ''They really don't feel like Timor's ready and it needs much more help before it can play at a level that other countries can."
East Timor gained independence in 2002 after three years of UN administration, which followed more than two decades of bloody guerrilla warfare during Indonesian rule.
But an outbreak of gang violence in 2006 prompted the UN Security Council to set up a new peacekeeping force, Unmit.
Following the mostly peaceful presidential and general elections this year, the UN is due to withdraw its troops from the country by December.
East Timor's officials will be keen to use Mrs Clinton's trip as a way to boost the nation's profile, says the BBC's Karishma Vaswani in Jakarta.
Although rich with natural resources, Timor has struggled to raise the standard of living of its people, with an estimated 40% of Timorese still living below the poverty line, says our correspondent.