Washington DC/IBNS, March 3 -- In a shift from his earlier hardline posture, US President Donald Trump said "boots on the ground" may not be necessary following the attack on the US embassy in Riyadh, Saudi Arabia, media reports said.

Earlier on Monday, Trump signalled that US military operations against Iran could continue indefinitely, dismissing questions about a timeline.

"Whatever the time is, it's OK," he told reporters at the White House. "We're already substantially ahead of our time projections. From the beginning, we projected four to five weeks, but we have the capability to go far longer than that. Whatever it takes, we'll do it."

He also brushed aside suggestions that he could lose interest in a prolonged conflict. "Someon...