Iran's supreme leader Ayatollah Ali Khamenei warns US attack would start 'regional war'

A man wearing a turban holds a folded piece of paper.

Ayatollah Ali Khamenei says the nation will deal a heavy blow to any country that attacks it. (Reuters: West Asia News Agency/Handout)

In short:

Iran's supreme leader says a United States attack on his country would lead to "regional war", his most direct threat yet after Donald Trump sent American warships to the Arabian Sea.

Mr Trump sent the US Navy ships to the region after Tehran's deadly response to anti-government protests, but has also brought up Iran's nuclear program as an issue he wants to see resolved.

What's next?

Mr Trump says he hopes to "make a deal" with Tehran, which has said it is ready for nuclear talks if its missile and defence capabilities are not on the agenda.