NEW YORK — World leaders will gather in solemn assembly next week above the sandy beaches of Normandy to mark the 75th anniversary of the world-changing D-Day invasion of France. It’s typically a heartfelt tribute to alliance and sacrifice and a unified vow for enduring unity, outweighing any national or political skirmish of the moment.

That’s what has some U.S. veterans and others worried about President Donald Trump’s attendance. The president has shown a repeated willingness to inject nationalistic rhetoric and political partisanship into moments once aimed at unity. For Trump, there is no water’s edge for politics, no veneer of nonpartisanship around military or national security matters.

The president, who did not serve in the military before becoming commander in chief, has feuded with Gold Star families, blasted political opponents on foreign soil, and mocked Sen. John McCain , a prisoner of war, for being captured by the enemy. Trump’s antipathy for the late senator was so well known that the White House this week requested that the Navy keep the USS McCain out of the president’s line of sight during a recent trip to Japan, so as not to rile the president.

It’s a pattern that is set to get more scrutiny in coming days, as Trump heads overseas for the D-Day memorial where he will be joined at the service by, among others, House Speaker Nancy Pelosi, a Democrat whom he has called “crazy Nancy” and warned not to try to impeach him.

“It’s unfortunate we have to be even concerned that this historic commemoration will be overly politicized, but this is the command climate he’s created and the reality we have,” said Paul Rieckhoff, founder and former head of the Iraq and Afghanistan Veterans of America. “We have to send our president. You go with the president we’ve got, and this is the president we’ve got. So we’re rightfully holding our breath for an event like this.”

More Than 9,000 Americans Died in D-Day Operation

More than 9,000 Americans died in the D-Day operation that marked a turning point in World War II, beginning the Allied push to drive the Nazis out of France and eventually Europe. On a bluff overlooking Omaha Beach, rows of white crosses and the Stars of David stretch as far as the eye can see — markers of sacrifices.

The president missed the other significant military commemoration of his term.

In November, also in France, Trump scuttled plans to honor the 100th anniversary of the end of World War I at Aisne-Marne American Cemetery. The White House said the president’s helicopter could not make it to the site because of bad weather. It did not explain why Trump could not make the 50-mile drive. His absence set off howls from many veterans.

Trump blamed the Secret Service and the next day went to a different cemetery outside Paris.

In recent days, he visited Arlington National Cemetery and spent Memorial Day on a naval ship in Japan.

“You are the ones keep going and striving, and keeping America safe, and strong, and proud, and free,” Trump said during the visit. He also wished everyone a “Happy Memorial Day,” a greeting some find off-key for a holiday dedicated to honoring dead servicemembers.

Plenty of Previous Presidents Have Embraced the Military

Ahead of the trip, the White House told the U.S. Navy to keep the warship rededicated in honor of Sen. McCain out of sight of the president. The president denied knowing about the request but said the gesture was “well-meaning” because he was no fan of McCain, a prisoner of war whom Trump once mocked by saying he preferred soldiers who “weren’t captured.”

Trump also sided with North Korean dictator Kim Jong-un over criticism of former Vice President Joe Biden. Some veteran groups were pleased Trump was attending the D-Day commemoration but urged him to leave the political broadsides at home.

“In situations like these, it’s best for President Trump to focus on his positive vision for reforming the Department of Veterans Affairs and advocating for a more restrained foreign policy,” said Dan Caldwell, a senior adviser for the conservative Concerned Veterans for America.

Plenty of previous presidents have embraced the military, identifying themselves with its power and patriotism. But Trump’s relationship with the armed forces — and the families of individual soldiers — has at times been uniquely fraught.

As a candidate, he feuded with the parents of Capt. Humayun Khan, who was killed in Iraq, and as president clashed with the mother of Sgt. La David Johnson, who died in Niger. Though Trump has been a cheerleader for the Pentagon, he is part of a recent trend of commanders-in-chief who did not serve in the military. He received a deferment that allowed him to not serve in Vietnam War due to bone spurs, but has been unable to remember in which foot, leading to accusations of draft dodging, including this week from 2020 rivals.

Trump Considered Issuing Pardons for Memorial Day

“You have somebody who thinks it’s all right to let somebody go in his place into a deadly war and is willing to pretend to be disabled in order to do it,” said Democrat Pete Buttigieg, the mayor of South Bend, Indiana, who served as a Navy intelligence officer in Afghanistan. “That is an assault on the honor of this country.”

And while a number of veterans groups have applauded Trump’s efforts to improve mental and physical health care to former officers, many of those same organizations sharply criticized Trump’s recent consideration to pardon several American military members accused of war crimes, including headline-grabbing cases of shooting unarmed civilians and killing an enemy captive.

“It is mind-blowing that these are the persons this administration is considering for pardons,” said Kristofer Goldsmith, an associate director for policy at Vietnam Veterans of America, one of several veterans’ groups that oppose the pardons.

Trump considered issuing the pardons for Memorial Day but later said he may wait for some trials to conclude. But his international trips have repeatedly been interrupted by distractions back home, and many around him fear that even a solemn World War II observance may not be enough to prevent the president from tweeting an attack at special counsel Robert Mueller or escalating tensions with his hosts, outgoing British Prime Minister Theresa May or French president Emmanuel Macron.