John Travolta as a soldier, cop, DEA agent or any sort of gun-weilding protagonist is simply not believable, therefore, the pretext for "Basic" is flawed before the story ever takes root.
Travolta reached his peak when he took top billing in "Saturday Night Fever", doing a great job of portraying a Brooklyn kid who is coming of age during the 70's disco era. But, outside of "Pulp Fiction" it's been all downhill after that, with a string of failures like "Stayin' Alive", "Broken Arrow", "Battlefield Earth", "Swordfish", and lest we forget, "Look Who's Talking II".
In "The Thin Red Line" Travolta played a U.S. Army General officer by method acting, evidently by imitating a talking plant. This (...) effort no doubt greatly contributed to the failure of that film to garner any sort of approval by veiwing audiences.
"Basic" is another such failure. Casting Travolta in a roles like the DEA agent he plays in this film is like a kiss of death for the entire project. For one thing, the idea that his character is a former Army Ranger is a hoot. Casting somebody like Pauly Shore or maybe even Martin Short as a a former Army Ranger would be more believable.
Very predictably, Travolta manages to stink up the whole story, which isn't all that great to begin with. Yet, with an extremely limited acting range, Travolta continues to crank out box office bomb after bomb after bomb.
Oh well... That's Hollywood politics. After all, no one ever went broke underestimating the sophistication of the American public...