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 whether Miller is officially advising Trump or only attended the one meeting. Miller serves...