Donald Trump has warned NATO allies the US would leave them to defend themselves if they don’t "pay their fair share".
In a rare formal foreign policy speech, the frontrunner for the Republican presidential candidacy said he would put American security "above all else" if elected.
Mr Trump reiterated his assertion that other countries must contribute to international security agreements, such as NATO, if they are to get the benefits of American military protection.
However, he also assured allies that the US will have a renewed commitment to them if he is elected as the 45th President of the United Sates. In the speech, which was read from a teleprompter, he said:
"To our friends and allies, I say America is going to be strong again, America is going to be reliable again. It's going to be a great and reliable ally again."
He called the foreign policy of President Barack Obama a "complete and total disaster" and said the US had "made the Middle East more unstable and chaotic than ever before".
But he left major questions over his own foreign policy plans, including those for defeating Daesh.
Mr Trump said the US must be "more unpredictable" adding that under his administration "their days are numbered. I won’t tell them when and I won’t tell them how".
The former reality TV star said "war and aggression will not be my first instinct" and he’d only deploy combat forces as a last resort.
Before the speech the democratic frontrunner, Hillary Clinton, said her potential rival has used "the most reckless rhetoric of any major presidential candidate in modern history".
Cover image: Michael Vadon