Donald Trump wants US allies to ante up if they want to continue under the “cloak of American protection,” according to his first detailed comments on his foreign-policy platform.

“We’re not being reimbursed for the kind of tremendous service that we’re performing by protecting various countries,” the Republican front-runner was quoted as saying.

Trump said he would boycott oil from Saudi Arabia and other allies ­unless they provide troops or funds to fight ISIS.

“If Saudi Arabia was without the cloak of American protection . . . I don’t think it would be around,” he told The New York Times.

Trump is open to removing US forces from Japan and South Korea if they did not take on the cost of housing and feeding troops on American bases there, the report said.

He argued that it is getting expensive to keep “defending the world.”

“We defend everybody. When in doubt, come to the United States. We’ll defend you. In some cases free of charge,” he said.

Trump pushed back against suggestions his foreign policy was “isolationist.”

“I am ‘America First,’ ” he said. “I like the expression.”

He vowed to renegotiate the Iran deal to extend restrictions on the country’s ability to build nuclear weapons while also allowing Iran to buy planes and other goods made in the United States.

“We gave them $150 billion, and they can’t spend it in our country,” he said.

The United States, in Trump’s view, has lost power economically and militarily for decades. He cited the Teddy Roosevelt era as the period when America’s might peaked.

“We have been disrespected, mocked and ripped off for many, many years by people that were smarter, shrewder, tougher,” he said.

Trump vowed to restore the country’s role as a global superpower. He suggested the United States has acted like a “big bully” and was “not smartly led.”

A cornerstone of the Trump doctrine is his “unpredictability” in dealing with foreign leaders.

“I wouldn’t want them to know what my real thinking is,” he said. “I would use trade, absolutely, as a bargaining chip.”

He defended US surveillance of allies like Israel and Germany, saying, “They’re spying against us.”

Trump said he would allow Japan and South Korea to develop their own nuclear programs instead of depending on America for protection from China and North Korea.

He wouldn’t rule out using nuclear weapons against an adversary, saying he would use nukes as an “absolute last step.”

But Trump held out hope he could facilitate the greatest deal of them all — lasting peace in Israel.

“I would have a better chance than anybody of making a deal,” he said.