Trump threatens to not help NATO countries if asked

US President Donald Trump said Monday that he could refuse to help NATO countries as pay back for the lack of support from member nations with the US military operation in Iran.

"We spent all of this money. And then when we want to maybe have help on small stuff... They say no we would rather not help," Trump said during a press conference in the Oval Office.

"Stupid thing to say, because we can say that to them if we want, and we might," he added.

Despite strained relations with the alliance, Trump is set to attend the NATO summit in Ankara, Turkey next month.