Regarding Kabul, we lack runway space, facilities, and enemy air defense suppression.
My grandfather was an Air Force loadmaster attached to forward bases for the Army and Marine Corps in Vietnam. The only way they were able to recover and launch cargo aircraft under heavy fire on short, improvised runways was by using RATO/JATO (rocket/jet assisted take-off) devices on the heavies. We haven't had a need for such things since the fall of Saigon. Kit wise we only have the C-130 and C-17's short take-off capabilities to rely on but they are slow when fully loaded. One whiz-bang from hadji could cripple or destroy a departing heavy. In all, a bad scenario. If we still held Bagram this wouldn't be an issue.
If the DoD is stating that we can't mount an airlift due to lack of aircraft then how in the Sam Hill fuck are deployments supposed to happen? Lack of facilities is reality right now but lack of aircraft? What happened to global force projection? You can't project shitting fuck with no planes.
I scarcely doubt a lack of aircraft is the cause of this newfound inability to mount a contested airlift. The military may have gone soft, but leadership is soft in the head.