US Secretary of State Hillary Clinton heads this week on a historic visit to Myanmar that aims not only to pry open the closed nation but to shake up the battle for global influence right on China's doorstep.

Clinton on Wednesday will become the top US official to visit the nation formerly known as Burma in more than 50 years as she tests the waters after dramatic -- but tentative -- reforms by the military-backed government.

Clinton is expected to meet both President Thein Sein and democracy icon Aung San Suu Kyi. She has said she will press for greater progress on human rights and democracy, without offering any let-up in biting US sanctions.

The United States has been careful not to raise expectations for a breakthrough. But Clinton's visit carries unmistakable symbolism as it seeks to advance US priorities in one of the countries most closely aligned with China.

Myanmar's "strategic importance to the United States is closely connected to concerns about rising Chinese influence," said John Ciorciari, an expert on Southeast Asia at the University of Michigan.

"To Beijing, Burma offers the possibility of natural resources and warm-water ports on the Indian Ocean that could be crucial in expanding China's naval reach," he said.

"Successful US engagement would lessen the likelihood of a strong Sino-Myanmar alignment in years ahead."

Beijing has provided the main diplomatic cover for Myanmar's leaders but the relationship is complicated, with some in the Southeast Asian nation resentful over China's overwhelming economic influence and historic border conflicts.

Myanmar recently defied China by shutting down work on an unpopular dam that would supply power across the border. Myanmar's leaders, known for deep distrust of the outside world, have reached out in recent years to India, Southeast Asia nations and, now, the United States.

For the United States, progress on Myanmar could help resolve a main stumbling block inside the Association of Southeast Asian Nations, giving new influence to the fast-growing -- and mostly US-friendly -- 10-nation bloc.

A stronger ASEAN would allow "China to grow and be secure but not use its new economic might to force neighbors' hands on issues related to sovereignty," said Ernie Bower of the Center for Strategic and International Studies.

US President Barack Obama's administration, while saying it wants a cooperative relationship with a rising China, has recently gone on the offensive amid suspicions over Beijing's intentions.

Obama recently announced the stationing of US troops in Australia -- a clear sign of US priorities at a time of tight budgets -- and has pushed ahead a trans-Pacific free trade agreement that for now excludes China.

Myanmar's military seized power in 1962 but since last year has held elections, nominally handed power to civilians and freed Suu Kyi from house arrest. The new government has opened a dialogue with the opposition and ethnic minorities.

While the United States and the opposition were at first cynical about the moves, Suu Kyi's National League for Democracy recently said it will re-enter mainstream politics. The party won 1990 elections but was never allowed to take power.

Even the most upbeat US policymakers acknowledge that Washington's influence is limited in a country so fearful of outside invasion that it suddenly moved its capital to the remote outpost of Naypyidaw in 2005.

The United States bans virtually all trade with Myanmar and any decision to end sanctions would need approval from Congress, with which exile groups have worked closely for years to pressure the generals.

Walter Lohman of the Heritage Foundation, a conservative think-tank that is often critical of the administration, welcomed Obama's phone consultations with Suu Kyi before the decision on Clinton's visit.

"The fact that the president called and got her blessing and that they're tying their policy to her makes it a very difficult decision to criticize," Lohman said.

But Lohman doubted how much further Myanmar would reform, suspecting that the leadership's main interest was to ensure it will be the chair of ASEAN in 2014.

"My guess is that the regime is calculating exactly how far it can go to get all of these things it is looking for without going too far to accommodate the political opposition," Lohman said.