The U.S. Central Command said Friday four crew members were killed when a refueling aircraft went down in western Iraq.

The military said the rescue efforts were ongoing and that the loss of the KC-135 aircraft was not due to hostile or friendly fire.

Six crew members were onboard at the time. There were no additional details provided on the fate of the two remaining members.

The incident came as the war with Iran, which has expanded throughout the Persian Gulf, approached its two-week mark. Israeli Prime Minister Benjamin Netanyahu offered a sobering forecast Thursday night: Israel may have weakened Iran's rulers, but its war effort may not be enough to topple them.

Netanyahu said Israel is working to create conditions that could enable Iranians to overthrow the country's regime. But when asked whether the goal could fail, he acknowledged he could not "say with all certainty" it would work.

"We are creating the optimal conditions for toppling the ⁠regime," Netanyahu said in his first press conference since the start of the war with Iran. "But I won't deny that I can't tell you with all certainty that the people of Iran will topple the regime — a regime is toppled from the inside."

A senior official in the region, speaking on condition of anonymity because they were not authorized to discuss internal deliberations, told NPR Israeli leaders are preparing the public for a longer conflict — and for an end to strikes without a negotiated agreement.

The official said Israel worries Iran and its allies could normalize intermittent missile fire, creating an intolerable "war routine" of periodic missile alerts and tit-for-tat retaliation.

President Trump, in a post on Truth Social, claimed the U.S. is "totally destroying" Iran's military and economy and insisted the war is being won. He also warned of more strikes ahead, writing "watch what happens" today.

Iranian and Lebanese health officials and Israeli authorities have reported more than 1,300 people killed in Iran, 687 in Lebanon and 12 civilians in Israel, as well as two Israeli soldiers fighting in Lebanon. Wednesday's aircraft crash over Iraq brings the number of U.S. service members killed to 11.