House Speaker John Boehner is demanding that the White House release a series of unclassified emails related to the Sept. 11 fatal terrorist attacks on the U.S. diplomatic mission in Benghazi, Libya.

Boehner is seeking emails Republican lawmakers say were sent the day after the attack from a senior State Department official to her superiors in which she reported that she told the Libyan ambassador that Islamic terrorists were responsible for the attack.

“The State Department would not allow our committees to keep copies of this email when it was reviewed,” Boehner said. “I would call on the President to order the State Department to release this email so the American people can see it.”

Boehner has been under pressure to impanel a select committee to examine whether the Obama administration did enough to protect diplomats in Libya and whether his administration tried to cover up the terrorism. Initially, the White House declared the attacks were prompted by a YouTube video that insulted Islam.

The letters Boehner is seeking would show the State Department was aware it was a terrorist attack well before Obama sent U.S. Ambassador to the United Nations Susan Rice on a round of Sunday talk shows to push the YouTube video as the cause.

According to top aide, Boehner won’t take “no” for an answer.

“It’s a warning that we want the emails, and we will pursue them,” the aide said.

A five-panel, Republican-led review in the House concluded that former Secretary of State Hillary Clinton personally approved of a reduced security plan in Benghazi before the attack. Clinton claims she was not involved in the decision.