Donald Trump is considering retired Marine general James "Mad Dog" Mattis for secretary of defense, according to a Sunday morning tweet from the president-elect.CNN reports that Trump and Mattis met and spoke on Saturday afternoon at one of Trump's golf courses in New Jersey. Afterward, Trump told reporters that Mattis was "the real deal."Mattis served in the Marines for 44 years, leading forces in Afghanistan and Iraq and earning a reputation for his success in 2004's battle of Fallujah. He went on to serve as a NATO commander and was promoted to head of US Central Command—meaning he ran military operations in the Middle East—during Barack Obama's first term in office.There's a rule against retired military officers serving as secretary of defense until they've been out of uniform for seven years, but Mattis—who retired in 2013—could get around that with a waiver that a Republican-controlled Congress would surely grant.Mattis is [respected](U.S. Embassy in Kabul, Afghanistan, on Sunday, May 8, 2011.) by both Democrats and Republicans for his years of service, and his plain-spoken, tough-guy style seems tailor-made to attract Trump—he got in a little bit of trouble for saying it was "fun to shoot some people" in 2005. He's also been an outspoken critic of the Iran nuclear deal. He's also gone on the record as being upset about Obama characterizing some US allies as "freeloaders," though Obama's sentiments have been echoed in much stronger terms by Trump.Trump has yet to make the appointment official, but seeing as how he flew Mattis to hang with him at his golf course and tweeted sweet nothings about him bright and early Sunday morning, the president-elect seems to be getting close to a decision.