United States intelligence agencies have warned that Iran is in “advanced stages” of plans to target US personnel abroad, prompting Washington to place staff on high alert in the Middle East, according to US officials and an official memo cited by Axios and The New York Times (NYT).

The alert comes as the US and Israel signal they may be preparing for a new military campaign against Iran, which Tehran has reportedly threatened to retaliate against, in part by targeting communications cables in the Gulf.

The heightened threat assessment has prompted Washington, already on guard over escalating attacks by Iran-backed Houthis, to trim Washington’s diplomatic presence in the Middle East, the NYT has reported, citing officials.

Here’s what we know about the latest US warning, and how it fits into the broader US-Iran conflict: A warning about Iranian plans to target US citizens was detailed in a memo sent by Director of National Intelligence Jay Clayton to Secretary of State Marco Rubio, first reported by US news site Axios.

In the memo, Clayton wrote that US agencies had received intelligence indicating that Iran has “substantially increased efforts to target US personnel” overseas, with lethal plots reaching “advanced stages” in the Middle East and other countries.

The NYT, which also reported on the memo, cited unnamed US officials as saying threats to American officials, including ambassadors, had been assessed in recent weeks, and that Iran had lined up potential targets in Europe. The officials said some intelligence indicates Iranian operatives are already active within the US.

Washington has not publicly commented on the memo, although the NYT cited a US official as confirming its authenticity on behalf of President Donald Trump’s administration.

Another official cited by the NYT played down Iran’s ability to execute attacks inside the US and elsewhere, saying it lacks the capacity to follow through on all its ambitions.

According to officials cited by the NYT, US agencies deem Iranian threats to US citizens in the Middle East to be “at the highest level” since the US-Israel war on Iran began in February.

This assessment is behind the US’s recent moves to withdraw staff posted in the region, the NYT added.

In the background are reported US and Israel plans to initiate a new military campaign against Iran following the US mid-term elections next month. On Friday, Trump said the US “may do another little epic fury”, using the codename for the US-Israel war against Iran that began on February 28.

On Wednesday, the US Department of State announced it was removing non-essential staff in its embassy in Saudi Arabia, citing escalating attacks by the Iran-backed Houthis in Yemen against Saudi infrastructure.

Staff levels have also been quietly reduced at other US diplomatic missions in the region, several US media have reported. That includes embassies in the United Arab Emirates, Bahrain, Kuwait, Qatar, Jordan and Lebanon, according to CNN.

A US official cited by the NYT said the threat of Houthi attacks and “Iranian terror plots targeting US officials” were driving US staffing decisions. Iran has not responded to news of the US intelligence memo accusing it of planning attacks on US personnel.

However, Iranian officials have repeatedly threatened and carried out attacks against US bases and those of its allies in the region. The Pentagon has confirmed that 21 US military personnel have been killed in the Middle East since the war on Iran began.

On Wednesday, Iran’s Islamic Revolutionary Guard Corps (IRGC) warned that Tehran would follow a new “offensive” strategy if the US renewed attacks.

That means Tehran would no longer limit its military operations to retaliatory strikes, said IRGC spokesman Hossein Mohebbi, adding that the quality, range and power of Iranian missiles had improved.

Tehran also has in-depth plans to target undersea communications cables in the Gulf in the event of new US-Israeli attacks, the Reuters news agency reported, citing two senior Iranian security officials.

Previously, Iran’s security chief Mohsen Rezaei warned that cables, data centres and artificial intelligence facilities across the region could come under attack if war with the US breaks out again.

Yes, US authorities have long accused Iran of being behind plots targeting US citizens, including assassination attempts against Trump on US soil.

In March this year, a Pakistani national was convicted by a US court of plotting to assassinate Trump and other US politicians on the orders of Iran’s IRGC.

An Iranian IRGC member was charged in 2022 with trying to assassinate former US National Security Advisor John Bolton. The individual allegedly “attempted to pay individuals in the United States $300,000 to carry out the murder in Washington DC or Maryland”, according to the US Department of Justice.

Last year, the US intelligence community warned that Iran would “continue to directly threaten US persons globally”, specifically targeting officials it believed were involved in the 2020 assassination of IRGC Quds Force commander Qassem Soleimani.

This month, the US abruptly withdrew bombers from an airbase in England, United Kingdom, citing concerns about a potential attack. That followed a security incident at the base, after which the UK arrested several men on suspicion of working with Iranian intelligence.