New Delhi, July 23 -- The first drone detonated against the exterior perimeter of the United States embassy compound in Riyadh in March. The second passed through the opening it created and detonated inside. No American casualties were announced. The CIA station embedded in the compound had been struck with a precision that Iranian drones had not previously demonstrated, and US intelligence analysts are still trying to determine how.

the station inside the Riyadh embassy and a separate facility in eastern Iraq. A memo produced by one Western intelligence service concluded that Russia had "likely played a role" in helping Iran identify and hit those targets.

One official put the total number of CIA-linked facilities potentially struck ac...