President Obama will nominate Jeh Johnson, former Defense Department general counsel, to be secretary of homeland security. (Brendan Smialowski/Getty Images)

President Obama will nominate Jeh Johnson, formerly the Pentagon’s top lawyer and a key figure in the administration’s debate over the legality of drone use, to head the Department of Homeland Security, according to White House officials.

The official announcement will take place Friday at the White House. Johnson, if confirmed by the Senate, would succeed Janet Napolitano, who announced she was leaving the Cabinet post in July.

As the former Defense Department general counsel, Johnson was responsible for the legal work at the nation’s largest bureaucracy. His job placed him at the center of some of Obama’s most important national security decisions, from the practice of targeted killings beyond America’s defined battlefields to the intervention in Libya.

“The president is selecting Johnson because he is one the most highly qualified and respected national security leaders,” said a senior administration official, speaking on the condition of anonymity to discuss the nomination before its announcement. “During his tenure at the Department of Defense, he was known for his sound judgment and counsel.”

The official added that Johnson was “responsible for the prior legal review and approval of every military operation approved by the president and secretary of defense” during Obama’s first term.

Jeh Johnson was nominated Friday to be the next Secretary of Homeland Security. But who is he? And how do you pronounce his name? (The Washington Post)

Johnson did not immediately respond to a request for comment. His impending nomination was first reported by the Daily Beast.

At DHS, Johnson would be overseeing a sprawling institution with 240,000 employees spread across 22 government agencies. The department’s mission covers counterterrorism and cybersecurity, but it also oversees issues as varied as the government’s response to national disasters and border security.

Johnson was among Obama’s early supporters in his run for the presidency in 2008, and developed a close rapport with the president during his first term. Former colleagues and associates said that Obama and Johnson shared a pragmatic approach to national security policy issues.

“He’s very much in line with the president in terms of caring about the rule of law and wanting to ensure the appearance of legal compliance,” said Jack Goldsmith, a Harvard professor who served as a senior Justice Department official during the George W. Bush administration. At the same time, Goldsmith said, Johnson is “not afraid to be aggressive to protect national security,”

Johnson was deeply involved in the administration’s deliberations on a range of sensitive policy issues, including the repeal of the ban on gays serving openly in the military, the so-far unfulfilled search for a way to close the detention facility at Guantanamo Bay, and the White House effort to develop clearer guidelines for the targeted killing of terrorism suspects overseas.

After leaving the Pentagon last year, he publicly questioned the idea of an indefinite war against terrorism.

“War violates the natural order of things, in which children bury their parents; in war parents bury their children,” Johnson said in a speech at the Oxford Union last November. “In its 12th year, we must not accept the current conflict, and all that it entails, as the ‘new normal.’ ”

Johnson was also involved in one of the most controversial counterterrorism questions of Obama’s first term, whether the United States could use an armed drone to kill a U.S. citizen who had joined al-Qaeda.

He and others concluded that the U.S. government had the authority to carry out a strike on Anwar al-Awlaki, who was born in New Mexico and became a senior figure in al-Qaeda’s branch in Yemen before being killed in a joint CIA-U.S. military operation in 2011.