US forces and air-defense missile batteries across the Middle East were placed on high alert overnight Monday to possibly shoot down Iranian drones as intelligence mounted about a threat of an imminent attack against US targets, two US officials tell CNN.
The alert reflects the heightened tensions between the US and Iran in the wake of last week's US drone strike that killed a top Iranian general, Qasem Soleimani. US officials have claimed the strike against the general was carried out to prevent an "imminent" attack in the region that put American lives at risk, but have so far declined to provide further details.
"There were indications that we needed to monitor the threats" even more closely than is already being done, one of the US officials said. The second official described it as "all Patriot batteries and forces in the area on high alert" against an "imminent attack threat."
Iran has put missiles on its drones that have been used in other attacks, including a significant attack on Saudi oil installations last year. While forces have already been on high alert for several days, they were even more vigilant Monday night, both officials said.
Based on the intelligence, the US was watching for potential attacks specifically against US locations in Iraq, Kuwait, Saudi Arabia, the United Arab Emirates and Jordan.
US intelligence also has observed Iran moving military equipment, including drones and ballistic missiles, over the last several days. US officials said the movement may be an Iranian effort to secure its weapons for a potential US strike, or put them in positions to launch their own attacks.
Tuesday morning, national security adviser Robert O'Brien said the US had intelligence leading to the Soleimani killing that American diplomats, facilities and military personnel were at risk of attack.
"He was plotting to kill, to attack American facilities and diplomats, soldiers, sailors, airmen and Marines (who) were located at those facilities, correct," O'Brien said during a gaggle with reporters at the White House.
O'Brien would not provide additional details on the threat, only saying the US had "strong evidence and strong intelligence."
Pressed as to whether there continues to be an imminent threat, O'Brien said, "I think the Iranians are talking about retaliating every day in the open sources and we're monitoring it and we're taking it very seriously."