Donald Trump utterly lacks the temperament to be president. He hasn’t even reached the Republican convention, no less the presidency, and he’s already demonstrating his foreign policy would be a nightmare disaster that would make the US—and the world—less safe.

During an interview with Piers Morgan on ITV’s Good Morning Britain, Trump threw a tantrum in response to criticism of his proposed “Muslim ban” by British Prime Minister David Cameron and newly elected London Mayor Sadiq Khan.

Khan, who is Muslim, quite reasonably took issue with the fact that, under Trump’s “ignorant” proposed policy, he would be prohibited from traveling to the US. Asked by Morgan to comment on Khan’s valid criticism, Trump said: “I think they’re very rude statements and frankly, tell him, I will remember those statements. They’re very nasty statements.”

And his response to Cameron calling his ban “divisive, stupid, and wrong” was even more absurd and potentially harmful: “It looks like we’re not going to have a very good relationship. Who knows, I hope to have a good relationship with him but it sounds like he’s not willing to address the problem either.”

This is not the behavior of a president. A president cannot take criticism of his policies personally and hold grudges that stand to undermine key diplomatic relationships with foreign allies.

Trump is signaling that his own brittle ego is more important than the security of the nation.

Hillary’s campaign didn’t mince words:

Nobody is better at proving that Donald Trump’s foreign policy would be disastrous than Donald Trump himself. With one short interview on ITV’s Good Morning Britain, Trump set off a media firestorm in the UK, stoking fears about the potential fraying of our decades-long special relationship, and what that would mean for the UK’s national security and standing in the world.

Instead of reflecting on why it might be that leaders in a nation that has long been our closest ally might find his proposal stupid, Trump challenged Khan to an IQ test and exclaimed: “Number one, I’m not stupid, okay? I can tell you that right now. Just the opposite.”

The president simply cannot be more concerned about reflexively defending his ego than working with our closest international allies, even if he doesn’t like what they have to say.

What Trump still doesn’t understand is that the office of the presidency is more important than the person who holds it, and the nation is more important than either.

As long as he continues to prioritize his own fragility over the best interests of the nation, he’s unqualified to lead—and he’s precisely the fool he’s accused of being.

(AP Photo/Richard Drew)