The party of Myanmar’s detained elected leader Aung San Suu Kyi called on Tuesday for her immediate release and for the junta to recognise her victory in November elections, a day after a military coup sparked global outrage.

The United States threatened to reimpose sanctions on Myanmar’s generals after they seized power and arrested Suu Kyi and dozens of her allies in dawn raids on Monday.

The Noble Peace laureate’s whereabouts remained unknown more than 24 hours after her arrest and her only communication has come in the form of a statement written in anticipation of the coup calling for protests against military dictatorship.

The U.N. Security Council was due to meet later on Tuesday, diplomats said, amid calls for a strong global response to the military’s latest seizure of power in a country blighted for decades by army rule.

The coup followed a landslide win for Suu Kyi’s National League for Democracy (NLD) in Nov. 8 elections, a result the military has refused to accept citing unsubstantiated allegations of fraud.

The army handed power to its commander, General Min Aung Hlaing, and imposed a state of emergency for a year, crushing hopes the poverty-stricken country also known as Burma was on the path to stable democracy.

The NLD’s executive committee demanded the release of all detainees “as soon as possible”.

In a post on the Facebook page of senior party official May Win Myint, the committee also called for the military to acknowledge the election results and for the new parliament to be allowed to sit. It has been due to meet on Monday for the first time since the election.

U.S. President Joe Biden called the crisis a direct assault on Myanmar’s transition to democracy and the rule of law, and said his administration would watch how other countries responded.

“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,” Biden said in a statement.

The crisis is one of the first major tests of Biden’s pledge to collaborate more with allies on international challenges, especially on China’s growing influence.

The United Nations led condemnation of the coup and calls for the release of detainees, in comments largely echoed by Australia, the European Union, India and Japan.