Human rights activists, some dressed in orange prison jumpsuits, protested in front of the White House Monday to demand that the Guantanamo Bay detention facility be closed, 10 years after it opened.
Members of the group Witness Against Torture, who launched their protest on Sunday, plan to maintain an around-the-clock vigil until Wednesday, the 10th anniversary of the arrival of the first prisoners at the US naval base in Cuba.
They are taking turns being locked in a cage that bears a sign denouncing "indefinite detention without trial."
Several human rights groups including Amnesty International have called for a large rally on Wednesday, which will include the formation of a human chain running from the White House to the US Capitol building.
Witness Against Torture plans similar protest events on Wednesday in Paris, Toronto, London, Brussels and Berlin.
The US government "continues to detain human beings without due process and has essentially thrown the Constitution out the window," Helen Schietinger, a spokeswoman for the group, told AFP.
"Our government is not treating people according to the principles that this country was founded on."
The US naval base at Guantanamo Bay, Cuba accepted its first prisoners from the newly drawn battlefields of the global war on terror on January 11, 2002.
President Barack Obama declared within a few hours of taking office in January 2009 that he would shutter the camp within a year, saying it was used as a recruiting tool for terrorists, and detrimental to US national security.
The protesters also demand the closure of the US military's Bagram prison in Afghanistan and the repeal of provisions of the 2011 Defense Authorization Act that authorized the indefinite imprisonment of suspected terrorists.