The president was reacting to Trump’s recent comments that he wouldn’t automatically rush to help NATO allies threatened by Russia. Those remarks have alarmed plenty of Republicans.

Obama said that while he certainly has no problem with “challenging our European allies,” it’s another thing entirely to say “we might not abide by the most central tenet of the most important alliance in the history of the world.”

The president declared Trump lacks “enough information or understanding” to say what he’s saying.