Why would the US military be making such a statement, unless Lord Trump has lined up our guys to fight Israel's war, for it, again?

Probably because Trump (or Hegseth) told them to say it - which they would have done regardless of whether our guys have been lined up to fight there or not.

Again, bluster. Trump's not going to refrain from making threats merely because he has no intention of backing them up with boots on the ground.

No one's going to push back against Hamas reasserting control as Israel withdraws...unless the IDF does, and right now Netanyahu can't be seen to be the one to break Trump's Peace Prize dreams first. Theoretically the parties could move quickly on getting a Board of Peace and an international security team in place - but even at all deliberate speed that's a process of weeks, not days. Which gives Hamas plenty of time to decide, "Nah, we'd rather stay in charge here."

YouTube: The Kinks - Do It Again (TheKinksVEVO)