While U.S. officials have urged Israel to help devise a clear plan for the governance post-war Gaza, Campbell's comments are the clearest to date from a top U.S. official effectively admitting that Israel's current military strategy won't bring the result that it is aiming for.

"In some respects, we are struggling over what the theory of victory is," Campbell said at a NATO Youth Summit in Miami. "Sometimes when we listen closely to Israeli leaders, they talk about mostly the idea of....a sweeping victory on the battlefield, total victory," he said.

"I don't think we believe that that is likely or possible and that this looks a lot like situations that we found ourselves in after 9/11, where, after civilian populations had been moved and lots of violence that...the insurrections continue."

Israeli Prime Minister Benjamin Netanyahu has repeatedly vowed to achieve "total victory" against Hamas, the Palestinian militant group that attacked Israel on Oct. 7 and killed 1,200 people and took 250 others hostage.

In response, Israel unleashed a relentless assault on the Gaza Strip, killing more than 35,000 people, according to the figures of the Gazan health ministry, and reducing the densely populated tiny enclave to a wasteland.

Campbell's comments come as Washington is warning Israel not to go ahead with a major military offensive in Rafah, the southernmost city of the Gaza Strip where over a million people who have already been displaced by Israeli attacks are taking shelter.

Likening the situation in Gaza to that of a recurring insurgency that the United States faced in Afghanistan and Iraq after its invasions there following the Sept. 11 attacks, Campbell said a political solution was required.

"I think we view that there has to be more of a political solution...What's different from the past in that sense, many countries want to move towards a political solution in which the rights of Palestinians are more respected," he said.

"I don't think it's ever been more difficult than right now," he added.