Donald Trump at the first work session of the North Atlantic council at the NATO Summit, July 11, 2018.

President Donald Trump on Wednesday demanded that America's NATO allies raise their domestic defense spending levels to 2 percent "immediately" instead of by 2024, as NATO had previously agreed.

https://twitter.com/realDonaldTrump/status/1017093020783710209

The tweet was Trump's latest provocation in what has been a combative day as he attends a NATO summit in Brussels.

Earlier in the day, the White House confirmed that Trump also demanded that the agreed-upon level of domestic defense spending — 2 percent — be doubled, to 4 percent of gross domestic product.

"The president raised this same issue when he was at NATO last year," said White House press secretary Sarah Sanders. "President Trump wants to see our allies share more of the burden and at a very minimum meet their already stated obligations.”