The United States assesses that Iran could carry out retaliatory attacks targeting American forces in the Middle East soon, although the US is still seeking a diplomatic resolution that would see Tehran forgo any attack, two US officials said on Monday.
One of the officials, who spoke to Reuters on condition of anonymity, said Iran's retaliatory attack could happen within the next day or two.
Shortly after, a source familiar with the details told The Jerusalem Post that an alert was received about the possibility of an Iranian strike on Al Udeid Air Base in Qatar.
Iran has threatened to retaliate after the US bombed the Fordow, Natanz, and Isfahan nuclear facilities early on Sunday morning.
US officials have warned Iran against hitting back at the US and President Donald Trump said after the strikes that any retaliation by Iran against the US would be met with a force far greater than that used in the weekend US attacks.
The chairman of the Joint Chiefs of Staff, General Dan Caine, said on Sunday that the US military had increased protection of troops in the region, including in Iraq and Syria.
The United States has a sizeable force deployed to the Middle East, with nearly 40,000 troops in the region. Some of them operate air defense systems, fighter aircraft and warships that can detect and shoot down incoming enemy missiles but their positions are vulnerable to attack.
US strikes Iranian nuclear sites in Operation Midnight Hammer
This comes after the US struck Iranian nuclear facilities in Operation Midnight Hammer.
The US conducted airstrikes on three Iranian nuclear sites, namely Fordow, Natanz, and Isfahan, US President Donald Trump confirmed on Truth Social on Saturday night.
"All planes are now outside of Iran's airspace. A full payload of BOMBS was dropped on the primary site, Fordow. All planes are safely on their way home," Trump wrote.
"We have completed our very successful attack on the three Nuclear sites in Iran, including Fordow, Natanz, and Esfahan. Congratulations to our great American Warriors. There is no other military in the World that could have done this," he added.
The entrances to the nuclear facility in Isfahan via underground tunnels were impacted, International Atomic Energy Agency (IAEA) General Rafael Mariano Grossi confirmed in a Sunday statement.
The statement said that in addition to Isfahan, the nuclear sites of Fordow and Natanz are confirmed hits.
US embassy in Qatar recommends sheltering in place, Qatar says situation stable
The US embassy in Qatar emailed US citizens in the Gulf country on Monday recommending that they shelter in place until further notice, triggering a slew of messages from various Doha-based institutions to employees and students while Qatar maintained the situation was stable.
The embassy's advice comes as Iran repeated earlier threats to retaliate against the United States after strikes on its nuclear sites.
The US embassy message noted that the recommendation was "out of an abundance of caution" and offered no further information.
Commenting on the message, Qatari foreign ministry spokesperson Majed Al Ansari said in a statement that the security situation in the country remained stable, adding that the embassy's advisory did not suggest any specific threat.
Al Ansari said Qatar was ready to take all necessary measures to ensure the safety of its citizens and residents.
Qatar hosts Al Udeid Air Base, the largest US base in the Middle East, which serves as the forward headquarters for US Central Command (CENTCOM) and accommodates approximately 10,000 troops.
The British government on Monday issued a warning recommending that UK citizens in Qatar shelter in place until further notice.
The recommendation, which was issued out of "an abundance of caution" it said, included no details.
Britain is prepared to defend its personnel and assets in the Middle East and also those of its allies, after having moved assets to the region on a precautionary basis earlier this month, Foreign Secretary David Lammy said on Monday.
"Be in no doubt, we are prepared to defend our personnel, our assets and those of our allies and partners," he told parliament.