The Biden administration has declared the military’s takeover in Myanmar as a “coup d’état,” according to senior State Department officials, triggering a halt of U.S. foreign aid to the country’s government.

The fast-unfolding situation presents a first foreign policy crisis to President Joe Biden, who argued during the 2020 campaign that he would “restore” U.S. leadership on democracy and human rights after four years of former President Donald Trump‘s “America First” focus.

His administration has also threatened to return U.S. sanctions on the Southeast Asian country’s government after they were lifted under the Obama administration to encourage Myanmar’s slow transition to democracy.

“The military’s actions over the last week and frankly prior to that have put that progress at grave risk. A very small circle of Burma’s military leaders have chosen their own interests over the will and well-being of the people,” a senior State Department official said Tuesday.

The military seized power on Monday, declaring a state of emergency, installing its commander-in-chief Min Aung Hlaing as acting president and saying it will hold elections in one year.

The country’s November parliamentary elections saw longtime pro-democracy leader Aung San Suu Kyi and her party expand their control in a landslide win, while the military-backed party took a drubbing. Despite the country’s election commission finding no evidence of widespread fraud, the military demanded that parliament’s new session, scheduled to start Monday, be delayed until an investigation was complete.

Since events unfolded Monday morning in Myanmar, U.S. officials have not had contact with the military leadership and have been unable to reach Suu Kyi or other party leaders, per the senior official.

The military’s leadership has argued its actions are justified under the constitution, but Suu Kyi’s party and many outsiders have called it a coup.

Now that the U.S. government has done the same, U.S. assistance provided directly to the government will be halted as the administration reviews all aid to the country — a total of approximately $109 million — only a small portion of which goes to the government.

“We’re going to be guided by our longstanding commitment to the people of Burma and their aspirations for democracy, peace, justice, and development,” the senior official told reporters during a briefing, noting exemptions for assistance to the Rohingya and other oppressed ethnic minorities, as well as for promoting democracy.

Since 1986, U.S. law has required the government to restrict foreign aid if a country’s military overthrows — or plays a role in overthrowing — a duly-elected government. That includes any economic development or military assistance, but exempts funds for democracy promotion or specific purposes, like countering drug-trafficking or terrorism.

“The United States removed sanctions on Burma 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,” Biden warned Monday in a statement.

While the State Department officials declined to preview any sanctions, the humanitarian situation in Myanmar is already precarious. Millions have been plunged further into poverty in the last year by the coronavirus and economic collapse, so any decision from the Biden administration will likely seek to soften the impact on the Burmese people.

“The key is to hit precisely where you want to leverage and not hurt the people of Burma. They’re already really hurting badly, and we want to make sure it’s the military that gets affected,” Derek Mitchell told ABC News Monday. Now the president of the National Democratic Institute, Mitchell served as U.S. ambassador to Myanmar from 2012 to 2016 — the first ambassador since the U.S. withdrew its envoy in 1990.

“But the United States has very limited leverage frankly,” he added, especially because there’s been little U.S.-Burmese engagement since Myanmar’s military began its violent campaign to drive out the Rohingya in 2017.

Asked by ABC News about that limited leverage, the senior State Department official conceded U.S. ties with the military are “extremely limited to virtually non-existent,” but declined to address what it means for the administration’s ability to have an impact.

A Muslim ethnic minority in the country’s northwest, the Rohingya have faced decades of persecution and violent oppression. But starting in August 2017, Myanmar’s military, under Min Aung Hlaing’s command, began a campaign to drive the Rohingya from their homes — killing thousands, raping women, burning villages and seizing land.

The United Nations has said the campaign should be investigated as genocide and crimes against humanity — labels that the U.S. House of Representatives, the U.S. Holocaust Memorial Museum, and other prominent voices have embraced. The case is pending now before the International Court of Justice at The Hague.

The Trump administration, however, stopped short and declared the assault “ethnic cleansing.” Biden’s Secretary of State Antony Blinken said last month that his State Department will review that decision and may declare a “genocide.”

Suu Kyi, who spent years under house arrest and received the Nobel Peace Prize, has defended the government’s attacks on the Rohingya, at times justifying them as part of a war against Islamist extremists in the province. That defense, including at the ICJ, has tarnished her global reputation as a democracy icon.

But now, world leaders have rallied to her party’s defense.

“The military’s seizure of power in Burma, the detention of Aung San Suu Kyi and other civilian officials, and the declaration of a national state of emergency are a direct assault on the country’s transition to democracy and the rule of law,” Biden said in his statement, calling on the international community to “come together in one voice to press the Burmese military” to relinquish power, free political prisoners, reopen communications and refrain from violence.

Many of Myanmar’s neighbors, however, have called the military takeover an “internal” matter for the country to resolve, including China and U.S. ally Thailand, which is governed by its own military junta after a 2014 coup. Still, U.S. officials are in “daily” contact with allies and partners in the region, the senior official said, to coordinate a response.

“I’m not suggesting that it’s obvious or easy, but this is the approach that has to be tried — to see if there’s any way to find some kind of coalition that leverages both carrots and sticks to make a difference,” said Mitchell.

Among the foreign capitals that U.S. officials appear to not be in touch with is Beijing, which has deep economic ties in the country and with the military, although its fiercely independent leadership is at times resentful of that. The senior State Department official declined to say whether the U.S. had reached out to the Chinese government about the scenes, hours after state media there labeled the coup a “major cabinet reshuffle.”

ABC News’ Ben Gittleson contributed to this report from the White House.