After Mr. Biden was informed of the Erbil attack on Christmas morning, he ordered the Defense Department to prepare response options, White House officials said. Later in the day, the president authorized strikes that were conducted around 8:45 p.m. Eastern time. Mr. Biden chose Kataib Hezbollah and affiliated facilities that had been used to launch unmanned aerial drone attacks, officials said. Last month, the United States struck an operations center and a command-and-control node south of Baghdad used by Kataib Hezbollah. The group's political wing is part of the coalition of Prime Minister Mohammed Shia al-Sudani of Iraq.