The left would be going absolutely ballistic over this if we had a Republican president.

WASHINGTON — The United States can use lethal force against a U.S. citizen overseas if that person is part of an enemy organization seeking to attack the U.S., according to a once-secret memo released Monday.

The 2011 killing of one such American — al-Qaeda leader Anwar Al-Awlaki — was justified because it was carried out under applicable laws of war, the memo said.

The Obama administration memo became public under a court order in a Freedom of Information Act lawsuit filed by the American Civil Liberties Union and The New York Times.

“The release of this memo represents an overdue but nonetheless crucial step towards transparency,” said ACLU Deputy Legal Director Jameel Jaffer. “There are few questions more important than the question of when the government has the authority to kill its own citizens.”

In the memo dated July 16, 2010, then-Acting Assistant Attorney General David Barron wrote that “the U.S. citizen in question has gone overseas and become part of the forces of an enemy with which the United States is engaged in an armed conflict.”

In addition, the target of the drone strike “is engaged in continual planning and direction of attacks upon U.S. persons from one of the enemy’s overseas bases of operations,” Barron write.