U.S. intelligence officials are warning that Iran has intensified efforts to target American personnel and citizens abroad.

There are also some alleged assassination plots reaching advanced stages, according to CBS News.

In an unclassified memo shared with Secretary of State Marco Rubio, Director of National Intelligence Jay Clayton warned that Iranian efforts to carry out lethal attacks against Americans have progressed significantly in the Middle East and other parts of the world.

The warning comes as the Trump administration considers whether to resume military action against Iran. 

In the meantime, U.S. diplomatic and military officials are adjusting staffing levels at facilities throughout the Middle East in response to growing security concerns of attacks from Iran.

The memo does not identify the specific countries or individuals allegedly being targeted. 

Clayton said the intelligence community is working to make sensitive intelligence available to a wider group of State Department personnel so they can better assess potential threats.