New York: Republican US presidential front- runner Donald Trump has vowed to pursue an "America First" foreign policy if elected, saying many nations including allies "ripped off" America while China has rebuilt itself from money that it has "drained out of the US".
Expounding his foreign policy priorities, Trump said he would consider pulling out American troops from Japan and South Korea if the close allies did not pay the US more.
Trump told the New York Times that he might stop buying oil from Saudi Arabia if it did not send troops to back US efforts to fight Islamic State militants.
The 69-year-old real estate billionaire, who has kept his momentum rolling despite concerted efforts by party establishment to thwart his presidential aspirations, insisted he was "not isolationist" but "America First".
He said: "We have been disrespected, mocked, and ripped off for many, many years by people that were smarter, shrewder, tougher.
"We were the big bully, but we were not smartly led. And we were the big bully who was the big, stupid bully and we were systematically ripped off by everybody."
"So America first, yes, we will not be ripped off anymore. We're going to be friendly with everybody, but we're not going to be taken advantage of by anybody," he said.
Trump cited the US debt - "soon to be USD 21 tn" - and linked it to the fact the US "defended the world".
"No matter who it is, we defend everybody. When in doubt, come to the United States. We'll defend you. In some cases free of charge."
He said that China, now the world's second largest economy after America, had rebuilt itself from money that has "drained out of the United States".
"They've done it through monetary manipulation, by devaluations. And very sophisticated. I mean, they're grand chess players at devaluation," Trump said.
He added: "I like China very much, I like Chinese people. I respect the Chinese leaders, but you know China's been taking advantage of us for many, many years and we can't allow it to go on."
Talking about the rise of China, he said the best way to halt Beijing's building of military airfields and anti- aircraft batteries on reclaimed islands in the disputed South China Sea was to threaten its access to American markets.
"We have tremendous economic power over China, and that's the power of trade," he said.
He declined to elaborate on his plans for dealing with the Communist giant, saying "I wouldn't want them to know what my real thinking is."
Trump said the US was "not being properly reimbursed" for protecting Saudi Arabia.
"Without us, Saudi Arabia wouldn't exist for very long. It would be, you know, a catastrophic failure without our protection.
"They're a money machine... And yet they don't reimburse us the way we should be reimbursed."
Trump also cited NATO, saying it was "obsolete" as the main international threat now was terrorism.
"NATO is something that at the time was excellent. Today, it has to be changed," he said, adding that the US bore "far too much of the cost of NATO".
He expressed a similar view about the US funding of the United Nations.
Trump said: "We get nothing out of the United Nations. They don't respect us, they don't do what we want, and yet we fund them disproportionately again."
Trump also slammed President Barack Obama's administration for seeking a political exit for Syrian President Bashar al-Assad while simultaneously fighting the Islamic State group as "madness and idiocy."
"I'm not saying Assad is a good man, 'cause he's not, but our far greater problem is not Assad, it's ISIS," he said.
Trump also referred to the criticism he had received for calling Brussels a "hellhole waiting to explode" but said that, after the deadly attacks on Tuesday, he had been proved right.
He spoke of the arrest before the attacks of key suspect Salah Abdeslam.
Trump, who has said he supports the use of some methods of torture in some cases, said that if Belgian authorities had "immediately subjected him to very serious interrogation - very, very serious - you might have stopped the bombing".
In the March 22 Republican primary in Arizona, Trump grabbed all the 58 delegates at stake in the state, thus, increasing his total to 739 delegates and further increasing the gap on delegate count with his nearest rival Ted Cruz who has 425.
To win the Republican presidential nominee, Trump needs 1,237 delegates.
He needs to win 52 per cent of the delegates in the rest of the Republican primaries. So far, Trump has won 19 States as against Cruz's victory in eight States so far.