Donald Trump is getting some national security advice from Florida Rep. Jeff Miller, a major coup for the candidate and one that could give him some needed gravitas on an issue he's had problems with in the past.

A Trump campaign source confirmed to NBC News that Miller attended Trump’s meeting with national security advisers on Capitol Hill this Thursday. The Florida Republican, who’s retiring this year, is seen sitting at the front of a photo Trump sent out on Twitter after the meeting. It’s unclear what Miller's actual role is, with a campaign source describing him as a "volunteer."

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

Miller serves as chairman of the Committee on Veteran’s Affairs and is a member of the Intelligence and Armed Services committees. He's known as a prominent voice on national security issues —particularly on veterans’ issues— on Capitol Hill.

In a series of print and television news interviews over the past few weeks, Trump has sought to lay out his foreign policy platform, cobbling together at times contradictory positions on U.S. engagement abroad, the use of ground troops, nuclear weapons and diplomacy into a “Trump Doctrine” that he’s characterized as “peace through strength." But it’s an issue on which he’s made numerous gaffes over the course of his campaign, and many critics see Trump’s unfamiliarity with foreign affairs as one of his biggest weaknesses in the race.

Miller’s support and stamp of approval could help Trump make up some of that lost ground. And his outspoken advocacy on the VA crisis is sure to be a boon for Trump, who routinely pledges to clean up the VA and offer better services to veterans on the campaign trail.

Miller’s position as a committee chairman is also the latest signal Trump may be making inroads with the Republican establishment, even as many in the party's leadership remain openly opposed to or critical of him.

Despite that opposition, Trump has made overtures in recent weeks to establish a presence on Capitol Hill and smooth over a rocky relationship with the Republican National Committee. His campaign announced Thursday the launch of his House Leadership Committee, tasked with congressional outreach. That same day Trump met with RNC Chairman Reince Priebus to discuss convention procedures.

Miller’s appearance at the Wednesday meeting is a sign the House Leadership Committee is already bearing fruit — an aide one of the committee co-chairs, California Rep. Duncan Hunter, said the California congressman recommended Miller to Trump’s team, and had a conversation with him a few weeks back convincing him to come on-board.