Obama Decries Trump's 'Lack of Preparedness'

President Barack Obama questioned Republican nominee Donald Trump's readiness to be commander-in-chief, in an interview broadcast Sunday.

Weighing in on Trump's suggestions that the U.S. might not meet its mutual defense obligations in NATO, Obama told CBS it highlighted a "lack of preparedness that he has been displaying when it comes to foreign policy."

Obama has repeatedly called on European allies to boost defense spending, but has not questioned America's role in the alliance.

Trump has repeatedly indicated that the United States might not come to the defense of a NATO ally -- a treaty obligation -- if they were not pulling their weight.

"Anybody who's been paying attention knows there is a big difference between challenging our European allies to keep up their defense spending, particularly at a time when Russia's been more aggressive, and saying to them, 'You know what? We might not abide by the central tenet of the most important alliance in the history of the world,'" Obama said.

Under Article Five of the NATO treaty, members agree to regard an attack on one member as an attack on all and promise to mobilize together to defeat the threat.