Director of National Intelligence Jay Clayton warned Friday that Iran has “substantially increased its efforts to attack American personnel” abroad, and that plots to kill Americans are reaching “advanced stages” in the Middle East and other countries. The warning, contained in an unclassified memo that was sent to Secretary of State Marco Rubio and obtained by CBS News, comes as the State Department adjusts staffing at diplomatic posts across the Middle East, and U.S. military peers endorse its footprint in the region, amid concerns about direct threats from Iran and threats. of the Iran-backed Houthi movement in Yemen. “The Iranians’ lethal conspiracy efforts against American citizens have reached advanced stages both in the Middle East and in some other countries,” Clayton wrote. The memo, which was issued as the Trump administration considers resuming military strikes against Iran, does not identify specific targets or countries where alleged plots are underway, nor does it indicate whether strikes may be imminent. Clayton said the U.S. intelligence community is working to downgrade sensitive information – received through various channels – so it can be shared more widely with State Department personnel. CIA Director John Ratcliffe received a copy of the memo. Axios was the first to report on the memo. The warning follows a series of precautions at US diplomatic facilities across the region. Earlier this week, the State Department ordered non-essential US embassy staff and their families to leave Saudi Arabia. Several other US embassies in the region adjusted their staffing under “restricted operations” status, allowing them to reduce staff numbers without having to make a formally ordered exit, CBS News previously reported. “When it comes to our staff at embassies, we are constantly evaluating new information about the security environment,” a U.S. official told CBS News on Friday. “The threat of Houthi attacks and Iranian terrorist plots against US officials are informing our decisions on staffing adjustments for embassies in RO. [Restricted Operations] State in the region.” A U.S. official and a senior U.S. military official also told CBS News this week that the military has been quietly reducing its footprint at posts in the Middle East due to continued threats. Houthi militants have stepped up drone and missile attacks against Saudi Arabia, targeting oil infrastructure and airports. An attack on Riyadh’s King Khalid Airport earlier this month killed at least a dozen people, including a U.S. citizen, and wounded hundreds more. Last weekend, US embassies in Saudi Arabia, Bahrain, Qatar, United Arab Emirates and other countries warned Americans to exercise caution due to Houthi attacks. Although the United States and Iran have refrained from attacking each other in recent weeks, President Trump has not ruled out restarting hostilities after next month’s midterm elections. Iran has also continued to take responsibility for attacks on oil tankers in the Strait of Hormuz at a rally. campaign in Florida on Friday, Trump suggested that the United States could launch another operation against Iran if Tehran failed to reach an agreement,” the president said, invoking the name of the US military campaign launched in February.