LOS ANGELES—Mitt Romney received his first intelligence briefing on Monday, just days after he came under fire for his response to deadly protests against United States diplomatic missions in the Middle East.

The Republican presidential nominee spent roughly two hours behind closed doors at the U.S. Federal Building in West Los Angeles on Monday afternoon. His campaign did not disclose who briefed Romney—saying simply it was someone from the intelligence community, according to spokesman Rick Gorka.

It's customary for major party candidates to receive national security briefings from the current administration after they are formally nominated at their party's convention. Romney and his running mate, Rep. Paul Ryan—who is also set to receive briefings this week—were required to undergo a security clearance process to receive the briefings.

Romney aides did not disclose how often the GOP candidate will receive an intel briefing or how long subsequent sessions would be.