They were slowly ramping up to it however by deploying the Heavy NCR Troopers and Desert Rangers though. I don't think the New California Republic is on a fully war footing when it comes to fighting the Legion. The Legion, for all of its formidability, never expressed interest in moving beyond the Mojave and the NCR (as seen through that asshole Chief Hanlon for example) just doesn't see the Legion as that much of a threat to the NCR. It's not war in the homeland like against the Brotherhood or Khans or Enclave. It seems fairly clear that the New California Republic is on a barely popular war of expansion to take the Dam and New Vegas and everything else in the region. I think it's like comparing Vietnam or Korea to World War Two to be honest. A serious conflict to be sure, but not a mortal one. The War in the Mojave, all things considered, seems to be a major brushfire war. The New California Republic can probably take this.