After the US left, ARVN got the equipment left behind. They had the 4th largest Air Force in the world.
And legendary graft.
US aid wasn't cut off but it was reduced from $1 billion to $700 million in 1974. That shouldn't have been enough to cause their collapse in 1975.
Ignore the Snickering Pooch: he has delusions of adequacy. The RVN collapsed after the dingbat Lefty Democrats made a big show of cutting support and since they had successfully eliminated President Nixon, the massive air support we provided during the ‘73 Easter Offensive wasn’t coming and they knew it.
The smirking mutt is a DU agitator.
Congress placed a $1 billion ceiling on military aid to South Vietnam for fiscal year 1974. This figure was trimmed further to $700 million by August 11. Military aid to South Vietnam in fiscal year 1973 was $2.8 billion; in 1975 it would be cut to $300 million. Once aid was cut, it took the North Vietnamese only 55 days to defeat the South Vietnamese forces when they launched their final offensive in 1975.
The biggest failure was not to defend South Vietnam as we promised to do if the North Vietnamese violated the Paris Peace Agreement. The ARVN suffered a total of 254,256 combat deaths.