Trump to meet Germany's Angela Merkel at the White House

— -- President Donald Trump will meet with German Chancellor Angela Merkel today at the White House — the first time the two leaders will meet. Although the U.S. and Germany are close allies, Trump and Merkel disagree on just about everything, from immigration and refugee policies to the future of NATO.

The two have very different leadership styles: Merkel is the disciplined, measured statesman; Trump is the boisterous businessman known for going off script.

But Merkel has never shied from criticizing Trump — when he was on the campaign trail, when he was president-elect and now that he is in office.

In November, when he threatened to withdraw from the Trans-Pacific Partnership (he did so days after his inauguration), she said she was “not happy” that the agreement “will probably not become reality.”

In February, the day after he tweeted that the press was the “enemy of the American people,” she talked about the importance of the press during a speech at the Munich Security Conference.

“I am for a free and independent press and have great respect for journalists. We have had good experiences here in Germany with respecting one another. We discuss divergent opinions but accept freedom of the press as an essential pillar of democracy,” Merkel said.

In the Munich speech, she urged the U.S. to support the European Union.

Before the United Kingdom’s Brexit vote last June, Trump backed the country’s withdrawal from the EU, and after the “leave” side won, he predicted other countries would follow suit. In an interview with The Times of London in January, he called the European Union “a vehicle for Germany.”

Merkel fired back, saying in a news conference, “I think we Europeans have our fate in our own hands.”

Among the biggest issues to be discussed in today’s meeting: immigration and the future of NATO, according to U.S. officials. ABC News breaks down the divide between Trump and Merkel on these hot-button topics.

Immigration and refugee policies

Trump has long blasted Merkel for her policy of welcoming refugees to Germany, including 1 million in 2015 alone.

“I think she made one very catastrophic mistake, and that was taking all of these illegals, you know, taking all of the people from wherever they come from,” he told The Times of London in January. “And nobody even knows where they come from. So I think she made a catastrophic mistake, very bad mistake.”

He added that he has “great respect” for Merkel.

In an August speech on terrorism he compared her policies to those of his then-rival, Hillary Clinton.

“In short, Hillary Clinton wants to be America’s Angela Merkel, and you know what a disaster this massive immigration has been to Germany and the people of Germany. Crime has risen to levels that no one thought would they would ever see,” he said.

A report released by the German Federal Office of Criminal Investigation in November 2015 found that refugees committed crimes at the same rate as native Germans. Another study, released in February by the Centre for European Economic Research, found that while there was no “crime epidemic” after the massive increase in refugees admitted to Germany, there were “muted increases” in some criminal activities, like “drug offenses and fare dodging.”

Merkel has defended her policies against claims of increased crime due to refugees.

“We have to look closely at the crime rate among refugees, and the picture is varied. That is also the right answer, that you have to differentiate,” she said in December.

“The fact that some people want to exploit that is something we have to withstand and defend ourselves against,” she added.

Merkel’s spokesman Steffen Seibert was quoted by a German news agency saying she was “convinced that even the necessary, resolute fight against terrorism doesn’t justify putting people of a particular origin or particular faith under general suspicion.”

Trump and Merkel spoke by phone on Jan. 29 for the first time since his inauguration, and a joint statement about the call did not mention his executive order on immigration, which suspended the U.S. refugee program and temporarily barred citizens of seven predominantly Muslim countries from entering the U.S.

The order was blocked by U.S. courts, and Trump released a revised version in March.

The future of NATO

During his presidential campaign, Trump put U.S. allies on edge by declaring NATO “obsolete” and calling into question whether he would come to the aid of some of the Baltic states if are attacked by Russia.

Since those comments, Vice President Mike Pence reassured those allies that the U.S. commitment to NATO is “unwavering.”

“Your struggles are our struggles. Your success is our success,” Pence said at the Munich Security Conference. “And ultimately, we walk into the future together.”

But the administration has not stopped pressing NATO members to pay their fair share. The NATO agreement recommends that members spend at least 2 percent of their gross domestic product on defense. Currently, only five nations meet that goal, and Germany is not one of them, spending only 1.3 percent.

“We will do everything we can in order to fulfill this commitment,” Merkel said at the Munich Conference. “But let me add, however, that I believe while NATO is very much in the European interest, it’s also in the American interest. It’s a very strong alliance where we are united together.”

A U.S. official told ABC News that Trump “looks forward to talking to the chancellor about how to strengthen the NATO alliance” and is “heartened” that Germany has agreed to meet the 2 percent goal in the coming years.

The official added Trump will ask Merkel about her experience with Russian President Vladimir Putin.

“He’s going to be very interested in hearing her insights on what it’s like to deal with the Russians,” the official said.

ABC News’ Jordyn Phelps contributed to this report.