Trump's Defense Secretary Jim Mattis has privately expressed concern to lawmakers the defense budget Trump has proposed is not enough to rebuild the country's military, according to CNN. Mattis has publicly aligned himself with the White House's request.

Why it matters: Republican defense hawks are not happy with Mattis' decision to stand down; the $603 billion defense budget isn't a 10% increase as the White House says, but instead is just 3% more than what Obama was already planning for 2018. Senate Armed Services Chairman John McCain and Chairman of the House Armed Services Committee Mac Thornberry are pushing for a number more like $640 billion.

Sticking point: The Pentagon was one of the few agencies in Trump's plan that got an increase in the first place, so it would be politically difficult to lobby for more at this point.