Attorney General Eric H. Holder Jr. told a Senate committee Wednesday that he expects President Obama to explain the legal rationale underpinning the use of armed drones to target and kill U.S. citizens overseas.

Obama said in his State of the Union speech last month that he would be more transparent about the targeted killing program, and Holder said the administration is struggling with the need to fulfill that pledge.

Under questioning from Democrats and Republicans on the Senate Judiciary Committee about the drone policy, including circumstances in which it might be appropriate on American soil, Holder said he expects “you will hear the president speak about this.”

“We have talked about a need for greater transparency in what we share, what we talk about,” said Holder, who added that with the release of more information, “there would be a greater degree of comfort that this government does these things reluctantly but also in conformity with international law, with domestic law and with our values.”

In recent weeks, the administration has released a number of secret Justice Department memos to the Senate Intelligence Committee that provide legal justification for the killing of U.S. citizens involved in terrorist plots targeting the United States and, more broadly, the use of drones to strike al-Qaeda and its affiliates.

Members of the Judiciary Committee are also demanding access to the memos, which have so far been limited to senators on the Intelligence Committee and one staff member for each of them.

“Congress has a significant role to play in conducting oversight of national security matters,” said Sen. Charles E. Grassley (Iowa), the ranking Republican on the Judiciary Committee. “We have the right to ask for and receive classified information — through appropriate channels and subject to protections — to determine if the activities of the executive branch are appropriate.”

Holder was questioned by Sen. Ted Cruz (R-Tex.) about whether it was constitutional to target a U.S. citizen on American soil if that person posed no imminent threat and was, for example, simply sitting in a cafe.

Holder said it would not be “appropriate.” Earlier in his testimony, he said the possibility of capture, a key factor in any decision, is markedly different between the United States and overseas.

Holder said the use of armed drones in the United States might occur when events like the Sept. 11, 2001, attacks or the strike on Pearl Harbor were underway.

Cruz said he plans to introduce legislation that would outlaw the use of drones for armed attacks in the United States.