My pet theory for improving the situation long term is fourfold. First, never agree to Laotian 'neutrality'; second, don't overthrow Diem (for all his problems, decided better than the revolving door of coups that followed); third, create a relatively solid front extending along ~Route 9 from the sea to the Mekong (eight divisions was considered enough for this); lastly, fund and oversee the expansion of the Thai army to secure Vietnam's strategic flank. The southern insurgency was highly dependent on supplies and manpower moved in from the north, so without the highways and oil pipelines of the Ho Chi Minh trail running right up to the wide western border of the RVN, the NLF is going to be significantly less effective. As the Southern insurgency withers on the vine, more ARVN units can get freed up for a strategic reserve, or else take the place of withdrawn American units on the northern cordon. Fighting on a shortened front between the sea and the Mekong, ARVN forces can be drawn up for defense in depth, making them more resilient against the conventional offensives of the NVA.