The United States will not free two convicted terrorists in return for U.S. hostages being held in Algeria, the State Department announced Friday.

Islamist militants who took over a natural-gas facility on Wednesday are demanding that the United States release “Blind Sheikh” Omar Abdel Rahman and Aafia Siddiqui. Rahman was convicted of planning the 1993 World Trade Center bombing, and Siddiqui, also known as “Lady Al Qaeda,” is in prison for shooting two Americans in Afghanistan in 2008.

“The United States does not negotiate with terrorists,” State Department spokeswoman Victoria Nuland said twice at her daily press briefing. She confirmed that an unknown number of Americans remain captive despite an Algerian military raid that reportedly freed several hundred hostages Thursday evening.

The al Qaeda-linked militants are also demanding an end to the U.S.-backed French intervention in neighboring Mali. Far from backing off, Nuland said the Obama administration was beefing up its training efforts for an African-led force to rout the militants from northern Mali.