New Delhi, July 8 -- President Donald Trump declared on Wednesday that the interim memorandum of understanding intended to end the conflict between the US and Iran was "over," signaling a dramatic collapse in diplomatic efforts and raising fresh concerns about a broader regional war.

Speaking in Ankara before the NATO summit, Trump dismissed the agreement that had been designed to provide a 60-day window for negotiations on a permanent peace settlement between Washington and Tehran. The temporary accord, brokered with Pakistani mediation, had already been under strain after indirect talks in Qatar ended without a breakthrough, according to Reuters.

Delivering some of his strongest remarks since the agreement was signed, Trump said:

"To...