Tuesday at CNN’s Republican presidential debate, Sen. Rand Paul (R-KY) and his opponent Gov. Chris Christie (R-NJ) battled over starting World War III with a no-fly zone in Syria.

When asked if a Russian plane encroached that no-fly zone would he be willing to shoot down the plane and risk war with Russia, Christie said, “I would do it. A no-fly zone means no-fly zone. That’s what it means. I have this plain language hang up. But I would not talk to Vladimir Putin. I would talk to Vladimir Putin a lot. I would say to him, listen, Mr. President, there is a no-fly zone in Syria. You fly in and it applies to you. And yes we would shoot down the planes of Russian pilots, if in fact they were stupid enough to think that this president is the same feckless weakling that the president we have in the oval office is right now.”

Paul countered, “If you are in favor of World War III, you have your candidate. Here’s the thing. My goodness, what we want in a leader is someone with judgment not someone so reckless as to stand on the stage and say ‘yes, I’m going to shoot down Russian planes. Russia flies in that air space. I may or may not be in love with the fact that they are there. But they were invited by Iraq and Syria to fly in that air space. If we announce a no-fly zone it’s a recipe for disaster and World War III. We need to confront Russia from a position of strength but not from a point of recklessness that would lead to war. This is something—this type of judgment is having that kind of judgment who you would appoint and conduct affairs that is important. When we think about the judgment of someone who might want World War III we might think about someone who would shut down a bridge because they don’t like their friends. They want to get a Democrat. I think we need to be very careful about that.”

After loud boos, Christie said, “I’ll tell ya what reckless is. Reckless is is calling Assad a reformer and allowing Russia to come into Crimea and Ukraine and inviting Russia into Syria to team with Iran. And the reckless people are the folks in the White House right now, President Obama and Hillary Clinton are the reckless people. And if you think that a no-fly zone is a reckless policy, you’re welcome to your opinion, but how is it working so far as we have 250,000 Syrians murdered and millions running around the world running for their lives. We need to try something else and that is not reckless.”