Well said popeye. US military forces, ground, naval, and air, forced the North Vietnamese to the negotiating table and the peace was made due to what the US military had accomplished. NVA forces were defeated in the South, the VC had ceased to be a major player after Tet, and the North was being bombed into rubble.
After the peace deal was made and we were leaving, the NVA took two years to resupply and get back in order and then they invaded and defeated the S. Vietnamese. The fact that we were a signator to that peace treaty and did little appreciable militarily to stop it was something that makred us amongst other free nations in the area for many years thereafter...and lingers to this day.
But, as you say, the US military did not suffer a military defeat there at all. As you say, it was our political policy and leadership that lost.