President Obama will announce Thursday that the White House plans to lift the ban on sending detainees from Guantanamo Bay to Yemen, Fox News confirms, a move that could effectively resume efforts to close down the prison. This week, the Pentagon asked Congress for more than $450 million for maintaining and upgrading the Guantanamo prison. More than 100 of the prisoners have launched a hunger strike to protest their indefinite detention, and the military earlier this month was force-feeding 30 of them to keep them from starving to death. Since his inauguration in January 2009, Obama has pushed for shutting the prison, signing an executive order for closure during his first week in office. He has faced resistance in Congress with Republicans and some Democrats repeatedly blocking efforts to transfer terror suspects to the United States. The law that Congress passed and Obama signed in March to keep the government running includes a longstanding provision that prohibits any money for the transfer of Guantanamo detainees to the United States or its territories. It also bars spending to overhaul any U.S. facility in the U.S. to house detainees. That makes it essentially illegal for the government to transfer the men it wants to continue holding, including five who were charged before a military tribunal with orchestrating the Sept. 11 attacks. Lawmakers have cited statistics on terror suspects striking again and argued that Obama has failed to produce a viable alternative to Guantanamo. Obama's speech at the National Defense University in Washington.is expected to reaffirm his national security priorities, but make no new sweeping policy pronouncements. Chief among the topics the speech will focus on, officials said, is the administration's expanded use of unmanned spy drones to kill hundreds of people in Pakistan, Yemen and other places where terrorists have taken refuge. Obama has pledged to be more open with the public about the scope of the drone strikes. But a growing number of lawmakers in Congress are seeking to limit U.S. authorities that support the deadly drone strikes, which have targeted a wider range of threats than initially anticipated. The president is expected to talk generally about the need for greater transparency in the drone strikes and may allude to the desire to give greater responsibility for those operations to the military. But he is likely to tread carefully on an issue that involves classified CIA operations. The U.S. military has begun to take over the bulk of the strikes, replacing the CIA in nearly all areas except Pakistan, according to an administration official who was not authorized to discuss the plans on the record and spoke on condition of anonymity. That shift in responsibility has given Congress greater oversight of the secretive program. In a letter Wednesday to Senate Judiciary Committee Chairman Patrick Leahy, Attorney General Eric Holder revealed for the first time that a fourth American citizen had been killed in secretive drone strikes abroad. The killings of three other Americans in counterterror operations since 2009 were known before the letter acknowledged the four deaths. Against the backdrop of last month's deadly double-bombing at the Boston Marathon, administration officials said Obama will highlight the persistent threat of homegrown terrorists -- militants or extremists who are either American citizens or have lived in the U.S. for years. The two Chechen-born suspects in the Boston attacks were raised in the United States and turned against America and its invasions of Iraq and Afghanistan only in recent years, investigators have said. Like the quandaries of drone strikes and Guantanamo, the rise of homegrown terrorism is nothing new. The Obama administration included homegrown threats in its National Security Strategy in 2010. However, such threats have increased as the power of Al Qaeda's central leadership has ebbed -- especially after Usama bin Laden was killed in his Pakistani hideout by U.S. special forces two years ago.