President Trump said he would support an Israeli attack to halt Iran from restocking its missile arsenal and would take U.S. action if Tehran sought to rebuild its nuclear program.

Iran is seeing its biggest protests in three years after the currency plunged to a record low against the dollar. The Central Bank governor resigned on Monday.

As Netanyahu meets Trump, intelligence suggests Iran accelerating chemical weapons work while facing unprecedented domestic unrest and economic crisis.

Unrest is triggered by a drop in Iran’s currency, as frustration with a persistent economic crisis rises.

At a joint press conference with Israeli Prime Minister Benjamin Netanyahu on Monday, President Donald Trump issued a warning about Iran, saying the regime "may be behaving badly" and invoking the phrase "where there's smoke,

Images show roads in Tehran filled with protesters shoulder to shoulder Monday, disrupting traffic and clogging roadways.

The currency’s slide has accelerated as oil revenues have shrunk under sanctions from the US, which briefly joined the war to bomb Iran’s nuclear sites. The country’s stubbornly high inflation rate rose to 42.2 per cent in December year on year.

On Monday, Trump warned Iran against attempting to rebuild its nuclear program as he welcomed Netanyahu to his Mar-a-Lago residence in Florida.