NEW YORK -- Police used bolt cutters to separate AIDS activists who had chained themselves to each other Wednesday in the lobby of the building that houses the U.S. Mission of the United Nations.

The protesters had come to the building on East 45th Street to rail against what they said was the United States' failure to do enough to fight the global epidemic.

Charles King, one of the organizers, said they were denied admittance to deliver a letter, addressed to U.S. Ambassador John Bolton, which prompted the sit-in and chaining.

Police said they took 21 people into custody for resisting arrest.

The protesters chained themselves in a circle in the lobby of the mission around a large poster that featured a blowup of the letter, while chanting "End AIDS Now!"

After police cut through the heavy chains to remove the protesters, some walked out and others, like King, had to be carried out.

The letter criticized the United States for not fulfilling everything it pledged at the U.N. General Assembly Special Session on HIV/AIDS in 2001.

"We're here to bring public attention to the fact that the United States signed the declaration on AIDS ... but it's failed to keep many of the promises it made," King said.

A spokesman for the U.S. Mission defended the U.S. government's contribution to fighting the disease.

"I thought they were coming to thank the Bush administration for its $15 billion in aid to fight this terrible disease," spokesman Richard Grenell said of the protesters. "After all, we are the largest donor, comprising over 50 percent of the world's funding for this epidemic."

The U.S. Mission said the government pledged $15 billion in 2002 to fight HIV/AIDS and is on track to exceed that contribution.