President Donald Trump was joined in the White House Monday by Japanese Prime Minister Shinzo Abe to announce the signing of a U.S.-Japan Trade Agreement and Digital Trade Agreement.

But overshadowing the president’s enthusiasm for the digital deal, which Trump called “a very big factor in the world,” was the recent decision by the administration to pull troops out of northern Syria, a move that has prompted accusations of abandoning longtime U.S. allies by even the most ardent Trump supporters.

Standing in the Roosevelt Room, Trump fielded an onslaught of questions on why the U.S. would step aside for a Turkish military operation against the same Syrian Kurds who battled alongside U.S. forces in the brutal fight against the Islamic State.

“I don’t want to stay there for the next 40 years," Trump said. “It’s not going to do anything. ... I campaigned on the fact that I was going to bring our soldiers home, and bring them home as rapidly as possible.”

Part of keeping that promise, Trump said, is not thrusting U.S. forces into even more conflicts that have no end in sight.

“We interject ourselves into wars, and we interject ourselves into tribal wars and revolutions and all of these things that are very — they’re not the kind of thing that you settle the way we’d like to see it settled. It just doesn’t — it just doesn’t work that way. ... And it’s time to come back home."

Pressed on the notion that Syrian Kurds have already lost thousands as a result of being mired in a civil war and a five-year fight against ISIS, only to find themselves at the mercy of Turkish President Recep Tayyip Erdogan, Trump responded, “That’s true. And we’ve lost a lot of fighters, too.”

Losing American service members, Trump emphasized, has been the worst part of performing his job as president.

“I have to sign letters often to parents of young soldiers that were killed," he said. "And it’s the hardest thing I have to do in this job. I hate it. I hate it. Afghanistan. I signed one the other day — Iraq, Syria. They get blown up by mines. They get taken out by a sniper.

“And I have to write letters to people. And we make each letter different. Each person is different. And we make them personal. But no matter what you do, it’s devastating. The parents will never be the same. The families will never be the same.”

In response to reports Monday of American troops pulling back from the northeastern border of Syria, Kurdish forces accused the U.S. of reneging on a commitment that has been forged in blood.

“I can understand the other side of it," Trump said. “But if you go by the other side, that means we should never, ever come home. ... We’re willing to do what we have to do, but there has to be an end game. And if you stay, it’s going to be the same thing.

“We’re not a police force."