Donald Trump is a man in a hurry.

In the few short months he has been in office, the US president has sought and failed to bring peace to Gaza and Ukraine. He has bombed Yemen. He has launched a global trade war. Now he is turning his attention, such that it is, to Iran.

This has always been on the president's jobs list. For Trump, Iran is unfinished business from his first term.

The issue remains the same as it was then: what can stop Iran seeking a nuclear weapon?

Iran denies it has any such ambition. But other countries believe the Islamic republic wants at the very least the capacity to build a nuclear warhead, a desire that some fear could spark an arms race or even all-out war in the Middle East.

In 2015, Iran agreed a deal with the US, UK, France, Germany, Russia and China. It was called the Joint Comprehensive Plan of Action (JCPOA).

Under its provisions, Iran would limit its nuclear ambitions - and allow in international inspectors - in return for getting economic sanctions lifted.

But Trump pulled the US out of the deal in 2018, claiming it rewarded terrorism by funding Iran's proxy militias such as Hamas and Hezbollah. The US reimposed sanctions.

Iran subsequently ignored some of the deal's restrictions and enriched more and more uranium nuclear fuel.

Analysts fear Iran could soon have enough weapons' grade uranium to make a nuclear warhead.

The International Atomic Energy Agency (IAEA) watchdog estimates Iran's stockpile of 60% enriched uranium could make about six bombs if it was enriched to the next and final level.

Within days of his inauguration, Trump restored his former policy of so-called "maximum pressure" on Iran.