'Countries we defend must pay for the cost of this defence,' Republican front-runner Donald Trump says in a speech underlying his foreign policy if he is elected as US president.
Republican front-runner Donald Trump vowed on Wednesday to seek better relations with Russia and China if elected president in November and said he would make US allies bear more of the financial burden for their defence.
In a major speech, Trump delivered a withering critique of Barack Obama's foreign policy, saying the Democratic president has let China take advantage of the United States and has failed to defeat DAESH terrorists. He pledged to "shake the rust off America's foreign policy."
The New York billionaire spoke the day after victories in five northeastern states that moved him closer to capturing the Republican Party presidential nomination for the Nov. 8 election.
With US-Russian relations strained over numerous issues including Moscow's support for Syrian regime leader Bashar al Assad, Trump said "an easing of tensions with Russia from a position of strength" is possible.
Trump, a real estate magnate, also said he would use US economic leverage to persuade China to rein in North Korea's nuclear programme.
"China respects strength and by letting them take advantage of us economically we have lost all their respect," he said.
Trump said he would call separate summits of NATO and Asian allies to discuss a "rebalancing" of the US financial commitment to their defence.
He was stern in charging that American allies have benefited from a US defence umbrella but have not paid their fair share.
"The countries we defend must pay for the cost of this defence. If not, the US must be prepared to let these countries defend themselves. We have no choice," Trump said.
Trump, a reality TV star, has never held elected office and has built support - particularly among white working class voters - with a no-nonsense style and populist pledges to "make America great again."
He set aside his rancorous campaign rhetoric for his address on foreign policy, delivered at a downtown Washington hotel.
Trump usually speaks in an off-the-cuff manner, but he delivered Wednesday's speech with the aid of a teleprompter as he sought to make himself appealing to more Republican voters.