U.S. President Barack Obama is due to deliver a major speech on May 23 on counterterrorism and the U.S. administration's drone program.
The White House has offered few indications on the contents of the speech, but reports say the president is expected to reaffirm his national security priorities.
Obama will deliver his address at Washington's National Defense University.
Reuters quotes an unnamed White House official as saying that the president will explain why the use of drones is "necessary, legal, and just."
The official said Obama is also expected to sign a "presidential policy guidance" detailing when Washington can use drones.
The use of drones to kill terrorism suspects has increased tensions with countries such as Pakistan and drawn criticism from human rights activists.
On the eve of Obama's speech, the U.S. administration revealed for the first time that four American citizens have been killed in drone strikes outside war zones. Attorney General Eric Holder made the admission in a letter to Congress.
Muslim militant cleric Anwar al-Awlaki was the first U.S. citizen known to be targeted and killed by a U.S. drone strike in September 2011 in Yemen.
His son, Abd al-Rahman Anwar al-Awlaki, and Samir Khan, also U.S. citizens, were later killed in Yemen but had not been specifically targeted.
Holder's letter describes the killing of cleric Awlaki as a "lawful target" because he "posed a continuing and imminent threat of violent attack against the United States."
A fourth American national, Jude Kenan Mohammed, was killed in Pakistan and was named for the first time in the letter. Mohammad was indicted by federal authorities in 2009 as part of an alleged terror plot to attack the U.S. Marine Corps base at Quantico, Virginia.
Before he could be arrested, authorities said, Mohammad fled the country to join jihadi fighters in the tribal areas of Pakistan.
Obama is also expected to address the issue of the U.S. military prison in Guantanamo Bay, Cuba.
During his 2008 election campaign, Obama pledged to close the Guantanamo Bay prison, but the detention center remains operational.
More than 100 out of a total of 166 detainees at Guantanamo are currently on a hunger strike, dozens of whom are being force-fed to keep them from dying. The strikers are protesting their conditions. Some have been held indefinitely without being charged with crimes.
With reporting by Reuters, BBC, AP, and dpa