A US naval strike group led by an aircraft carrier has deployed to Middle Eastern waters, the United States said on Monday, as Tehran warned it was ready to hit back at any American attack launched in response to a crackdown on anti-government protests.

The protests started in late December, driven by economic grievances, but turned into a mass movement against the Islamic Republic, with huge street demonstrations for several days from January 8.

But rights groups have accused authorities of quelling the movement with unprecedented violence, shooting into crowds of protesters under the cover of an internet shutdown that has now lasted 18 days — the longest Iran has ever imposed.

US President Donald Trump has previously threatened to step in, saying last week that Washington was sending a “massive fleet” to the region “just in case”.

The deployment of the USS Abraham Lincoln carrier strike group dramatically boosts American firepower in the region.

The United States backed and briefly joined Israel’s 12-day war against Iran in June, and while Trump last week appeared to step back from his threats of new military intervention, he has never ruled the option out.

The Lincoln’s strike group has arrived in the region, US Central Command said in a post on X, adding the ships were “currently deployed to the Middle East to promote regional security and stability”.

‘Regret-inducing response’

Iran’s foreign ministry warned on Monday of a “comprehensive and regret-inducing response to any aggression”.

Ministry spokesman Esmaeil Baghaei said Iran was “confident in its own capabilities”.

In apparent reference to the Lincoln, he added: “The arrival of such a battleship is not going to affect Iran’s determination and seriousness to defend the Iranian nation.”

Meanwhile, a new anti-US billboard has appeared in the central Enghelab Square in Tehran that appears to show an American aircraft carrier being destroyed.

“If you sow the wind, you will reap the whirlwind,” its English-language caption reads.

State news agency IRNA quoted the commander of the Iranian navy Shahram Irani, as saying on Monday: “Iran’s naval power is not merely defensive but also acts as an anchor of stability in the region.”

In Lebanon, Hezbollah organised a rally in support of the Islamic Republic featuring an address by its leader, Naim Qassem, who warned, “a war on Iran this time will ignite the region”.

Iran’s Gulf neighbour, the United Arab Emirates, which hosts a US airbase, said it would not allow attacks on Iran to be launched from its territory.