It is, but it also isn't, given the US forces on Okinawa, and also just generally in the region. The US military is not a force that exists for homeland defense, it's a force designed purely to project power across the ocean.

> engage militarily

This can mean a lot of things though. A steady flow of matériel and intelligence given to an island that's basically a giant and highly-defended mountain-range is going to go a very long way.

> is any US president

I mean in the last 150 years they've shown a remarkable willingness to intervene, more than once in proxy wars against the Chinese.