How so?
We have fewer troops deployed overseas then we have had in many decades. Yet during both the Cold War and post-Cold War period, and during the wars in Iraq and Afghanistan when we had literally hundreds of thousands of troops actually fighting overseas, recruitment was much stronger. And we're not even at war now.
The recruiting problem has absolutely nothing to do with deployment of US troops overseas, or overseas alliances. Zip. Zero. Nada.
The problem is that the military has deliberately adopted leftist social policies that discourage many young men from joining the military. If you don't support "diversity, equity, and inclusion", oppose "toxic masculinity" and "whiteness", and support transgenderism, you aren't welcome.
That means a whole lot of people who might otherwise enlist choose not to. That's why recruiting numbers suck. Hell, recruiting numbers would probably be better if we were still fighting a real war and couldn't afford to do that crap.
You are conflating recruiting and overseas deployments.
The question really is: what are our troops defending? Certainly not our own borders. We are being invaded everyday and yet we enthusiastically send our troops abroad to serve the security interests of other countries. That’s indefensible when you’re ignoring your own.
Do you know how many foreign military bases we have around the world? Do we really need that many?