The US is sending a Patriot missile-defense system to the Middle East amid escalating tensions with Iran, the BBC reported on Saturday.
A warship, USS Arlington, with amphibious vehicles and aircraft on board, will also join the USS Abraham Lincoln strike group in the Gulf.
US B-52 bombers have also arrived at a base in Qatar, the Pentagon said.
It said the moves were a response to a possible threat to US forces in the region by Iran, without specifying. Iran has dismissed it as nonsense.
Tehran has described the deployments as “psychological warfare” aimed at intimidating the country.
There are about 5,200 US troops currently deployed in neighboring Iraq.
The US has not said what threat they face and the latest Pentagon statement on Friday said only that Washington was “ready to defend US forces and interests in the region”.
It added that the US did not seek conflict with Iran.
The Patriot system can counter ballistic missiles, cruise missiles and advanced aircraft.
Officials told US media the USS Arlington had already been scheduled to go to the region, but its deployment was brought forward to provide enhanced command and control capabilities.
The USS Abraham Lincoln passed through the Suez Canal on Thursday, US Central Command said.
Iran’s semi-official Isna news agency quoted a senior Iranian cleric, Yousef Tabatabai-Nejad, as saying that the US military fleet could be “destroyed with one missile”.
Last year, US President Donald Trump unilaterally withdrew from a landmark nuclear deal America and other nations had agreed with Iran in 2015.
Under the accord, Iran had agreed to limit its sensitive nuclear activities and allow in international inspectors in return for sanctions relief.
Last month, the US also blacklisted Iran’s elite Revolutionary Guard Corps, designating it as a foreign terrorist group.
The White House proceeded to end exemptions from sanctions for five countries – China, India, Japan, South Korea and Turkey – that were still buying Iranian oil.
The sanctions have led to a sharp downturn in Iran’s economy, pushing the value of its currency to record lows, driving away foreign investors, and triggering protests.
The Trump administration hopes to compel Iran to negotiate a “new deal” that would cover not only its nuclear activities, but also its ballistic missile program and what officials call its “malign behavior” across the Middle East.
Iran has repeatedly threatened to retaliate to the US measures by blocking the Strait of Hormuz – through which about a fifth of all oil consumed globally pass.
Earlier this week Iran announced that it had suspended two commitments under the 2015 accord in response to the economic sanctions the US had re-imposed.
It also threatened to step up uranium enrichment if it was not shielded from the sanctions’ effects within 60 days.
European powers said they remained committed to the Iran nuclear deal but that they “reject any ultimatums” from Tehran to prevent its collapse.
