WASHINGTON — President Joe Biden on Monday threatened new sanctions on Myanmar after its military staged a coup and arrested the civilian leaders of its government, including Nobel laureate Aung San Suu Kyi.

Biden assailed the country’s army for the coup, calling it a “direct assault on the country’s transition to democracy and rule of law.” The coup in Myanmar, also known as Burma, has also been roundly condemned internationally.

“The United States removed sanctions on Burma over the past decade based on progress toward democracy,” Biden said in a statement. “The reversal of that progress will necessitate an immediate review of our sanction laws and authorities, followed by appropriate action. The United States will stand up for democracy wherever it is under attack.”

Myanmar has been a Western democracy promotion project for decades and had been a symbol of some success. But over the past several years, there have been growing concerns about its backsliding into authoritarianism. Disappointment with Suu Kyi, the former opposition leader, has run high, especially over her resistance to reining in repression of Rohingya Muslims in the country’s west.

An announcement read on military-owned Myawaddy TV said Commander-in-Chief Senior Gen. Min Aung Hlaing would be in charge of the country for one year. It said the seizure was necessary because the government had not acted on the military’s claims of fraud in November’s elections in which Suu Kyi’s ruling party won a majority of the parliamentary seats up for grabs and because it allowed the election to go ahead despite the coronavirus pandemic.