It was JFK who started shipping troops to Vietnam by the many 1000s, why didn’t the military assassinate Truman or Eisenhower who only had some advisors there?
They went through wwii and were spending a lot to develop an arsenal of nuclear weapons against the soviets, plus funding the newely created intel agencies, and in the 50s the soviets took over/helped take over the satellite easter european countries. Further they were involved in Korea so there was war occurring. There was no need to convince them to fund anything, but Eisenhower did warn of the mi complex at the end of his presidency.