The military seizure of power in Myanmar halts the country's progress toward democracy and presents an initial diplomatic challenge to U.S. President Joe Biden, who has pledged to rally the world to meet its common challenges.

The takeover reverses one of the few concrete results of the American rebalance away from the Middle East and toward Asia under former President Barack Obama's administration, where Biden served as vice president.

"The international community should come together in one voice to press the Burmese military to immediately relinquish the power they have seized, release the activists and officials they have detained," Biden said in a statement Monday, using the Southeast Asian nation's old name.

"We will work with our partners throughout the region and the world to support the restoration of democracy and the rule of law, as well as to hold accountable those responsible for overturning Burma's democratic transition," he said. He had been briefed Sunday by national security adviser Jake Sullivan.

Washington is "taking note of those who stand with the people of Burma in this difficult hour," Biden added.

The president also threatened to reinstall sanctions, saying that the U.S. removed sanctions over the past decade based on progress toward democracy. "The reversal of that progress will necessitate an immediate review of our sanction laws and authorities, followed by appropriate action," he said in the statement.

The remarks flesh out Washington's stance after White House press secretary Jen Psaki said in a statement Sunday that the U.S. "will take action against those responsible if these steps are not reversed."

Biden -- who had promised as a presidential candidate to stand up for democracy and human rights around the world -- called the military takeover led by commander in chief Min Aung Hlaing and the detention of such civilian leaders as State Counselor Aung San Suu Kyi and President Win Myint a "direct assault on the country's transition to democracy and the rule of law."

Biden and his foreign policy team have repeatedly emphasized the need to strengthen America's alliances and work with democratic allies to defend against the spread of authoritarianism. Myanmar's democratic backsliding will test the administration's ability to pull such an effort together.

Myanmar's military will certainly be looking to how Washington responds, but the U.S. has limited leverage and "the most important external actors are China, India and Japan," said Josh Kurlantzick, senior fellow for Southeast Asia at the Council on Foreign Relations, a New York-based think tank.

China is the regional superpower. India, another major neighbor, gifted a Soviet-era Kilo-class submarine to Myanmar in October, a move that many analysts saw as an attempt to counter Beijing's clout in the region.

In part driven by geopolitical interest and partly driven by seeking an alternative manufacturing hub with lower wages than China, Japan has been leading a wave of investment into the country, dubbed Asia's "last frontier." More than 400 members of the local Japan Chamber of Commerce and Industry were operating there at the end of May 2020.

Asked about the situation Monday, Chinese Foreign Ministry spokesperson Wang Wenbin did not criticize the military takeover and stressed the friendly ties between the two countries. "We hope that all sides in Myanmar can appropriately handle their differences under the constitution and legal framework and safeguard political and social stability," he said.

Walter Lohman, director of the Washington-based Heritage Foundation's Asian Studies Center, said that "there will be some who will say we cannot be too tough on Burma because it will give room for the Chinese to consolidate its relationship."

But that concern should not stand in the way of the U.S. reinstating sanctions, as "the truth is that Beijing already has a relationship that far outstrips Washington's," Lohman said.

Myanmar's progress toward democracy has stopped just a decade after the country threw off the yoke of half a century of military rule.

The junta years saw the military crush pro-democracy demonstrations and keep Suu Kyi, then a leader of the movement, under house arrest. The U.S. imposed multiple rounds of sanctions starting in 1997, barring American companies from investing in, importing goods from, or participating in financial transactions involving Myanmar.

The junta began transitioning to civilian rule, starting with the general election in 2010, in hopes of getting Western sanctions lifted and allowing the struggling economy to grow.

Washington responded to these efforts. Obama in 2012 became the first sitting U.S. president to visit Myanmar, and big American companies including Coca-Cola and Mastercard began entering the market.

This owed partly to concern about China, Myanmar's neighbor to the north. It was in America's interest to counteract Beijing's influence in Southeast Asia while tapping into the growth of a country that has been called the region's "last economic frontier."

This trend seemed to accelerate after Suu Kyi took the reins of the government's civilian component after her party won the 2015 general election.

But the dynamic began to shift in 2017, with the crackdown on Myanmar's Rohingya Muslim minority. Both the military and Suu Kyi herself faced international condemnation over the crisis, throwing cold water on foreign investment.

China, which has shown more understanding toward Myanmar's handling of the issue, has helped breathe new life into the country's economy, providing support for port, rail and power plant projects through the Belt and Road infrastructure initiative. Given the risk of renewed Western sanctions, the military likely sees Beijing as a shield from more economic pain.

Beijing has sought to maintain a balance between Myanmar's political and military leadership in its diplomatic approach to the country. President Xi Jinping met with both Suu Kyi and Hlaing during a 2020 visit to the country, as did Foreign Minister Wang Yi on his Southeast Asia tour this past January.

Myanmar is not the only country whose backsliding on democracy is reflective of Beijing's rise and Washington's relative decline in the region.

Authoritarianism has also gained sway in Thailand, where the military took over in a 2014 coup and still enjoys substantial influence; in Cambodia, where Prime Minister Hun Sen's party holds full control of Parliament after cracking down on opposition; and in the Philippines, where President Rodrigo Duterte's government is waging a brutal war on illegal drugs.

Biden has brought in familiar faces from the Obama administration for his diplomatic team and is putting democracy and human rights at the core of his foreign policy. But the U.S. has lost much influence in Asia, after the Obama-era rebalance petered out and just-departed President Donald Trump largely neglected the region. Regaining lost ground will be no easy task.