Any such increase would be almost impossible for smaller countries in Europe to achieve, and it is not clear that the capitals of Europe could muster the public or political support for such breathtaking increases in defense spending.
Trump has vented over the lack of progress in Afghanistan, other officials say.
North Atlantic Treaty Organisation leaders are spending the second day of the summit moving on from President Donald Trump's harsh criticism on Wednesday for not meeting military spending obligations and focus instead on ending the war in Afghanistan.
"Everyone in the room thanked me", he said.
Several current U.S. officials and other former officials and advisers with direct knowledge said the White House had not yet formally ordered the review but they were preparing for a government-wide appraisal in the next few months. He did not specify which countries had committed to what.
Earlier on Thursday, the USA president posted a series of messages on social media, hammering United States allies during the second day of meetings with leaders of the military alliance.
If the White House is as confused about the nature of the threat we face from Mr. Putin as it seems to be, a meeting between our president and his Russian counterpart for which there is no record could not be more concerning.
Following the summit, NATO Secretary General Jens Stoltenberg was careful not to contradict the president's claim of a substantial increase in spending but was only able to directly point to members' existing 2 percent commitments.
"But Germany is totally controlled by Russia", Trump added.
He continued to criticize Germany over an $11 billion pipeline deal with Russian Federation. We have a tremendous relationship with Germany.
"What's more surprising, the fact that the President Trump is calling them out on that or that previous presidents haven't?" he asked.
In 2017, the alliance saw its biggest increase in defense spending "in a generation", he said, signaling to his aggrieved ally in the White House that "we see that all Allies have started to increase defense spending based on the national plans we have agreed to develop past year".
"And frankly maybe everyone is going to have a good relationship with Russian Federation".
It was the most recent in a series of demands and insults that critics fear will undermine the decades-old alliance, coming days before Trump sits down with Putin at the conclusion of his closely watched European trip.
Trump has described the spending situation as "disproportionate and not fair to the taxpayers of the United States".
A joint summit declaration issued Wednesday underlined NATO's support for Ukraine and its aspirations for membership of the alliance, pending domestic reforms.