President Trump said the “massive” responsibilities that come with the White House surprised him, but the one that weighed the heaviest was the launching of a cruise-missile attack on Syria in retaliation for a poison-gas attack.

“I never realized how big it was,” he told the Associated Press in an interview conducted Friday and published Sunday. “Everything’s so… like, you know the orders are so massive.

“Number one, there’s great responsibility,” the president continued. “When it came time to, as an example, send out the 59 missiles, the Tomahawks in Syria. I’m saying to myself, ‘You know, this is more than just like, 79 (sic) missiles. This is death that’s involved,’ because people could have been killed.

“This is risk that’s involved, because if the missile goes off and goes in a city or goes in a civilian area… and if this missile goes off and lands in the middle of a town or a hamlet,” Trump said as his first 100 days in office come to an end on Saturday. “Every decision is much harder than you’d normally make.”

The real-estate mogul remarked how the human factor plays a role in governing.

“Pretty much everything you do in government involves heart, whereas in business, most things don’t involve heart,” he said. “In fact, in business you’re actually better off without it.”

The US military launched a Tomahawk missile strike at a Syrian air base on April 6 after President Bashar al-Assad’s regime killed scores of citizens — including women and children — in a chemical attack a few days earlier.

Trump, who was criticized for remarking that “nobody knew that health care could be so complicated” during efforts to repeal and replace ObamaCare, admitted the US government is a sprawling, complex enterprise.

“The financial cost of everything is so massive, every agency,” he said. “This is thousands of times bigger, the United States, than the biggest company in the world.”

In the freewheeling interview, Trump lists getting Judge Neil Gorsuch on the Supreme Court and his relationships with German Chancellor Angela Merkel, Chinese President Xi Jinping and Egypt’s leader Abdel-Fattah el-Sisi as among his proudest accomplishments in his first 100 days.

“I think I’ve established amazing relationships that will be used the four or eight years, whatever period of time I’m here,” said Trump, who campaigned on an “America First” platform. “I think for that I would be getting very high marks because I’ve established great relationships with countries.”

He also said he didn’t endorse Marine Le Pen’s candidacy for president of France and denied that comments he made about last week’s possible terror attack in Paris will encourage terrorism.

“I think it discourages terrorists, I think it discourages. I think what we’ve done on the border discourages it,” he said. “I’m not going to have it in this country. I’m not going to let what happened to France and other places happen here.”

And Trump said he didn’t strike a deal with el-Sisi to win the release of Aya Hijazi, a 30-year-old Egyptian-American aid worker held in Cairo for thee years. Trump said he raised the issue of Hijazi’s captivity when el-Sisi visited the White House in April.

“No deal,” Trump said. “He was here. He — I said, ‘I really would appreciate it if you would look into this and let her out.’ And as you know, she went through a trial. And anyway, she was let go.”