If not for Israel, the USA would have to establish their own military base in the Middle East, which would cost the US far more than aid they give to Israel. The US has a bargain here in helping keep their ally and “always available to be a USA military base” secure.
Btw, I am in no way a Zionist, I recognize galus including in Israel, and at the same time, I of course want whatever will keep all Yidden safe.