WASHINGTON (Reuters) - President Joe Biden said Iran cannot act with impunity and warned Iran to “be careful” when asked what message he was sending the country with the U.S. air strikes in Syria. “You can’t act with impunity. Be careful,” Biden told reporters while traveling to survey the damage from a severe winter storm in Texas. The United States carried out air strikes authorized by Biden against facilities belonging to Iranian-backed militia in eastern Syria on Thursday, in response to rocket attacks against U.S. targets in Iraq.