WASHINGTON: The “big wave” is yet ‌to come in the war with Iran, US President Donald Trump told ​ CNN on Monday, adding that ​Washington did not know who ⁠the country’s new leader would ​be following the killing of Ayatollah ​Ali Khamenei. “We haven’t even started hitting them hard. The big wave hasn’t even ​happened. The big one is ​coming soon,” Trump said, telling CNN it ‌was ⁠unclear who was now leading the country. Earlier during the day, US General Dan Caine, the chairman of the Joint Chiefs of Staff, said it would take time to achieve US military objectives in Iran and additional US casualties were expected. The US-Israeli air war against Iran expanded on Monday with no end in sight. The US military said Kuwait’s air defenses had mistakenly shot down three American F-15E fighter jets during an Iranian attack. “This is not a single overnight operation. The military objectives that CENTCOM and the Joint Force have been tasked with will take some time to achieve, and in some cases will be difficult and gritty work,” Caine told reporters. He added that the United States continued to send additional troops to the Middle East, even after a massive military buildup. Caine’s comments came a day after US President Donald Trump suggested that strikes against Iran could go on for the next four weeks. A fourth US service member on Monday died of injuries sustained in the US operation against Iran. During the same press conference, U.S. Defense Secretary Pete Hegseth said military operations against Iran would not lead to an “endless war,” though he acknowledged that the operation would not be complete overnight. Hegseth said the aim was to destroy Tehran’s missiles, navy and other security infrastructure. “This is not Iraq. This is not endless ,” Hegseth said. In the biggest US foreign policy gamble in decades, President Donald Trump launched the campaign alongside Israel on Saturday against a foe that had tormented the United States and its allies for generations. Even with the US-Israeli strikes, leaders in Iran have shown no sign of yielding power. Military experts say US and Israeli air power, with no armed force on the ground, may not be enough to drive them out. Meanwhile, scores of Iranians have been reported killed in strikes, including several that hit apparent civilian targets.