The president previously called the decision the "most significant investment in our military and our war fighters in modern history."
The president has warned Europe can no longer rely on Trump's United States—and is busily preparing France and its allies to face off Islamist threats and an increasingly ambitious Russia.
The president made the claim in an unscheduled press conference Thursday and said he told allies, "I would be very unhappy if they didn't up their commitment very substantially."
The summit is an opportunity to present an updated strategy for the transatlantic alliance, but President Trump is unlikely to follow the script.
Even if the Pentagon budget were cut in half, the United States would still outspend China, Russia, Iran, and North Korea combined.
The Navy is going forward with plans to purchase its variant of the F-35 jet, which has been described as the most expensive weapon system ever.
The president wants to boost defense spending and gut funding for other agencies.
Trump's pledge comes amid mounting evidence that potential enemies have built new anti-ship weapons able to destroy the expensive fleet of carriers.
Trump said on Twitter that the F-35 program's cost "is out of control" and that "billions of dollars can and will be saved" after his inauguration.
TVs, DVD players and mini-fridges were required in every room, according to the report.
The president wants to repeal all spending limits; Republicans only want military spending.
Former top U.S. military commander slams Europe's foreign policy as "wishful thinking" in light of spending cuts.
Report outlines bleak prospects for British military under political parties' spending plans.
The American way of waging war needs a long, cool rethink.
"I am not saying that US doesn't spend a whole lot, but that most don't understand why," Jon Davis, a sergeant of Marines and Iraq veteran writes