It may seem perverse to wonder whether the USA is withdrawing into an isolationist shell only a couple of days after it has orchestrated a rather modest coalition into military action against the Houthis. World Policeman, or what? Yet I can't help feeling this may be the reflex action of a former bruiser who was in the process of retreating from the fray ("leave it babe, he ain't wurf it") when somebody rushed up to take another swipe at him anyway.
Well, maybe that will persuade him to get stuck right back in there again. People inside and outside America have been urging its government since the first few years of the Monroe Doctrine to disengage from the ROTW and concentrate on self-sufficiency and domestic affairs. That long-lived policy saw American governments intervening all over the place, to no obvious good effect, for many years. There was always a "leave it babe" faction advocating the opposite. But overseas intervention is a hard habit to break.
But what would getting stuck right back in there entail, in a world of truculent Russians, increasingly confident & capable Turks, Iranians and N.Koreans, an out-of-control Netanyahu, and, errr, China?
For one thing, it would require military spending on an implausible scale. The USA of Bush / Clinton / Bush / early-Obama not only operated with no serious Russian threat and only the early signs of Chinese (and Iranian) upsurgence, but also with far and away the biggest & best-equipped armed forces on the planet. Not any more. The Peace Dividend has been taken in no uncertain terms, and the USA could no more fight the fabled "two big wars and one small one, all at the same time" than fly over the moon. (And it's not very good at flying over the moon any more, either.)
So what are the voices that will prevail, longer-term, in Washington? There is certainly a bellicose "pivot to China" lobby, which thinks in terms of defending Taiwan and the South China Seas. There's another modest coalition of nations behind this one, too (always us and the Aussies, eh? Us with our two naked aircraft carriers and all.) But drill down deeper, and the practical measures being advocated by all except the outright headbangers are a great deal less offensively-minded than in years gone by. The talk is of porcupine defence, stand-off weapons, drone-swarms etc - not marine divisions storming up the beaches under 100% air-superiority. Just as with the Roman Empire: when you trade in your stabbing sword for a long-sword, you're basically on the defensive, however widely you cast the perimeter.
And that's the warlike lobby - many of whom would withdraw substantially from the Middle East, too - not to mention looking to Europe for the bulk of support for Ukraine. The outright isolationists & Trumpists would cheerfully deal with China - perhaps in return for their taking N.Korea out of the equation.
And what will Starmer do then, poor thing? Some, of course, think he'll rush to Rejoin. There could conceivably be an intelligent offering from the EU on that score. But, interestingly, his track record as DPP was of shameful, grovelling obeisance to Washington, which seems to be a deep instinct for him.
He'd certainly keep the RAF busily bombing on whatever coordinates Biden dictates. While old Joe is still slugging it out at the bar.
 What were we doing there? The answer is obvious: the traditional combination of (a) the general policy of sticking with our biggest & most important ally, come what may (not entirely without merit, though Wilson never saw fit to gratify Johnson in Vietnam); and (b) the age-old tradition of us in these islands: show us a good fight, and we're in! (a.k.a. oi'll foight any t'ree of yuz!)
 It's been argued that the only thrust under the Monroe Doctrine, broadly conceived, with genuinely strategic justification was the annexation of Hawaii in 1898. The others, all over Latin America and even beyond, were generally deeply controversial within the USA itself
 What peace? - Ed