American missiles targeted sites across Iran on Friday, as US President Donald Trump threatened Tehran and its allied Houthi group in Yemen with 'major military punishment,' but kept the door open for a diplomatic agreement.

Trump told reporters at the White House: 'We are talking to them. I think they are serious, and I think they are dealing more seriously this time than ever before, but that does not mean reaching an agreement.'

In response to a question about an exit strategy from the war, Trump outlined two options: 'There is a military exit consisting of continuing what we are doing now and even increasing the pace of strikes, and there is a smarter strategy of reaching an agreement,' concluding: 'We are on standby and ready to move.'

This came two weeks after the collapse of the temporary truce that was supposed to end the war, as Iranian armed forces responded by firing on American bases in neighboring Arab countries, warning residents of the potential bombing of non-military buildings used by US troops.

Trump had threatened in recent days to expand the target list to include energy facilities and bridges in Iran, and to send ground forces to take control of Kharg Island, the center of Iranian oil exports, as well as to bomb a deep underground site linked to the nuclear program known as 'Picaxe Mountain,' though he confirmed on Friday that he has not yet decided on executing new major attacks.

On the economic front, the Strait of Hormuz represents the most sensitive point in this conflict that erupted about five months ago, killing thousands, exacerbating global inflation, and sparking fears of an economic recession.

The Houthis, who control northern and western Yemen, announced a naval blockade on Saudi Arabia, which has diverted millions of barrels of oil daily through a pipeline to the Red Sea, avoiding the near-total blockade imposed by Iran on the Strait of Hormuz.

After the Houthis announced they had targeted two Saudi oil tankers on Thursday, Trump confirmed that he would hold Iran responsible for any future attacks carried out by the group.