The U.S. has prepared for what could be significant attacks by Iran or its proxies in the Middle East as soon as this week, White House national security spokesperson John Kirby said on Monday.
Kirby said the U.S. had increased its regional force posture and shared Israel's concerns about a possible Iranian-backed attack after Iran and Palestinian Islamist group Hamas accused Israel of carrying out the assassination of a Hamas leader in Tehran last month.

"We share the same concerns and expectations that our Israeli counterparts have with respect to potential timing here. Could be this week," Kirby told reporters.
"We have to be prepared for what could be a significant set of attacks," he said.