London — President Trump, who has repeatedly threatened to withdraw from NATO and once called it "obsolete," surprised many by kicking off a two-day visit to London on Tuesday for the transatlantic alliance's annual summit by defending it against criticism from France. After French President Emmanuel Macron's suggested that NATO had suffered "brain death," Mr. Trump called the remark "very insulting."

Mr. Trump declared Macron's comments to be a "very, very nasty statement, essentially to 28 countries," adding, "nobody needs NATO more than France." As he sat alongside Macron, however, Mr. Trump did not continue to criticize the French leader. Mr. Trump said he believes Macron wants the best for NATO, but also wants it to serve the most vital functions.

President Donald meets French President Emmanuel Macron at Winfield House, Tuesday, December 3, 2019, in London. Evan Vucci / AP

Asked if he better understands what Macron meant, Mr. Trump said, "Well we just began discussing NATO, and what I'm liking about NATO is that a lot of countries have stepped up I think really at my behest. And also yourself, you're close to that level," the U.S. president added, addressing his French counterpart.

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The 70-year-old NATO alliance was founded to defend Europe from the Soviet Union. These days, it's supposed to be a united effort to guarantee the freedom and safety of member countries, but there is plenty of infighting.

"We are making real progress, most importantly on the burden sharing," NATO Secretary-General Jens Stoltenberg said while meeting with Mr. Trump in London Tuesday morning. He added that the U.S. president's "leadership on defense spending is having a real impact."

Mr. Trump said he discussed with Stoltenberg "the flexibility so that we have not just with one area of the world ... we have all areas of the world because NATO's a lot different than it was."

But NATO is also different than it was even three years ago, Mr. Trump emphasized, largely because of his push for other member nations to contribute more to their own defense.

"When I came in, I was angry at NATO, and now I've raised $130 billion," Mr. Trump said, referring to the amount Stoltenberg says European members and Canada will have added to their collective defense budgets by 2020. "And yet you still have many delinquent — you know I call them delinquent when they're not paid up in full."

Of NATO's 29 members, only nine spend at least two percent of their GDP on defense. The United States is reducing its contribution to NATO's central budget, CBS News White House correspondent Paula Reid reports.

Seated alongside Macron, Mr. Trump also weighed in on the protests in Iran, claiming the U.S. doesn't support the protesters even though his own secretary of state said otherwise a day earlier. Asked if the U.S. supports the protesters in Iran, Mr. Trump responded, "I don't want to comment on that, but the answer is no. But I don't want to comment on that." On Monday, Secretary of State Mike Pompeo said the U.S. is supporting the protesters in Iran who are revolting against the regime.

After those comments stirred concern, however, the president's Twitter account clarified the matter.

"The United States of America supports the brave people of Iran who are protesting for their FREEDOM. We have under the Trump Administration, and always will!" Mr. Trump's account said.

The president soon clarified that he thought the question was whether the U.S. supports the Iran protesters financially.

But even in London, Mr. Trump could not escape questions about the ongoing impeachment inquiry in Washington. On Wednesday, the House Judiciary Committee is holding its first impeachment hearing on Capitol Hill, intended to weigh in on whether Mr. Trump's actions regarding Ukraine constitute impeachable offenses.

"This is a witch hunt by the Democrats. It's a continuation — it's been going on for three years," Mr. Trump said Tuesday. He added later that the "impeachment hoax" is "going nowhere."

"The Republican party on this whole impeachment hoax has been like glue, because they know it's a hoax."

The president also ripped House Intelligence Committee Chairman Adam Schiff, calling him a "deranged human being."

When the "shoe is on the other foot," Mr. Trump said, and there's a Democratic president one day, Democrats won't want to have a precedent for Republicans to easily impeach a Democratic president.

Mr. Trump also announced that the next G7 summit will take place at Camp David next year, after the administration was forced to undo an announcement that it would be held at his Florida resort.

On Tuesday, the president also attended a fundraiser in London to benefit his presidential campaign and the Republican National Committee (RNC), raising $3 million, the RNC confirmed to CBS News.

In the evening, Mr. Trump and first lady Melania Trump attended a reception at Buckingham Palace hosted by Queen Elizabeth, and a reception at 10 Downing Street organized by British Prime Minister Boris Johnson.