Six weeks since Trump paused Operation Epic Fury for a ceasefire, talks to end the war have largely stalled.
Iran submitted a new offer to the United States this week, but its public accounts of it repeat terms previously rejected by Trump, including demands for control of the Strait of Hormuz, compensation for war damage, lifting of sanctions, release of frozen assets and the withdrawal of US troops from the area.
Trump said on Monday, and again on Tuesday, that he had come close to ordering a new bombing campaign but had put it off at the last minute to give more time for diplomacy.
"I was an hour away from making the decision to go today," Trump told reporters at the White House on Tuesday.
Iran has repeatedly threatened to retaliate for any new attacks by striking countries in the Middle East that house US bases. On Wednesday it suggested it would also hit targets further afield.
"If aggression against Iran is repeated, the promised regional war will this time spread far beyond the region, and our devastating blows will crush you," the Revolutionary Guards said in a statement carried on state media.
"The American-Zionist enemy... must know that despite the offensive carried out against us using the full capabilities of the world's two most expensive armies, we have not deployed the full power of the Islamic revolution," the Guards said in a statement on their Sepah News website.
Citing Iranian diplomatic sources, official news agency IRNA meanwhile announced a visit to Tehran by Pakistan's Interior Minister, his second in less than a week.
