GOP security expert explains why Trump's views on nuclear weapons should scare us to death

Joe Scarborough dropped a bombshell on Wednesday morning when he claimed that Donald Trump repeatedly asked a national security expert during a briefing why the United States bothers having nuclear weapons if it never uses them.

While there's some reason to doubt the veracity of Scarborough's story -- after all, why would he just sit on this news until after Trump had won the nomination? -- we do know that Trump has asked in the past why America bothers stockpiling a nuclear arsenal if it's never used.

During a town hall with Chris Matthews this past March, Trump refused to take using nuclear weapons off the table if he were president, and said he'd even consider using them in Europe if he had to.

Matthews at the time seemed genuinely shocked by Trump's remarks.

"[American allies] are hearing a guy running for president of the United States talking of maybe using nuclear weapons," Matthews said. "Nobody wants to hear that about an American president."

"Then why are we making them?" Trump asked. "Why do we make them?"

John Noonan, a Republican national security expert and former adviser to Jeb Bush and Mitt Romney, put out a tweet storm on Wednesday that showed just how dangerous this sort of thinking is.

The key here, as Noonan sees it, is that the reason nuclear weapons have been such an effective deterrent is that it's the United States' policy to never strike first with a nuke. Even suggesting that this policy could change could create geopolitical turmoil.

"[The] idea that nukes would be used, say over Raqqa or Mosul, simply because we have no more allies and it's a simple, easy fix is nauseating," Noonan writes. "Simply signaling that you're open to using strategic weapons as a tactical solution rewrites the rule book. Russia, China, others will respond. Nuclear deterrence is about balance. Trump is an elephant jumping up and down on one side of the scale. So damn dangerous."

Check out Noonan's full tweet storm below.