WASHINGTON: US President Donald Trump said on Monday that the United States would hit Iran 'hard' after the two foes exchanged fire for the first time in weeks. His Treasury secretary also pledged to continue a pressure campaign aimed at weakening Iran's economy.

After six months of war, the two countries remain at an impasse. Iran keeps the strategic Strait of Hormuz closed, while the US maintains a counter-blockade of Iranian ports.

On Sunday, the United States carried out strikes on an Iranian island in the Strait of Hormuz. Iran quickly retaliated by attacking US military targets in the Middle East.

The exchange raised concerns about a return to major hostilities. Trump's comment, reported by a Fox News reporter who spoke to him briefly, was: 'We're going to hit them hard.'