U.S. intelligence finds Iran has "substantially increased" its efforts to target American diplomats and officials in the Middle East and beyond, with lethal plots reaching "advanced stages," according to an Oct. 23 memo to Secretary of State Marco Rubio obtained by Axios.

Why it matters: U.S. officials say the intelligence is one reason the State Department is drawing down personnel at several American embassies across the Middle East, amid mounting fears of a broader regional conflict.

U.S. officials also fear that Iran-backed Houthi rebels in Yemen could expand their attacks beyond Saudi Arabia to other countries in the region.

Adding to the volatile security environment is the prospect of renewed U.S.…