Your recollection is wrong
Timetable of troop withdrawals: [link|http://faculty.smu.edu/dsimon/Change%20Course/Change-Vietout.html|http://faculty.smu.e...ange-Vietout.html]
According to [link|http://faculty.smu.edu/dsimon/Change-Viet4.html|http://faculty.smu.e...Change-Viet4.html], his Cambodia invasion was announced on April 30, 1970, at which point 115,500 troops had already been withdrawn (over 20% of the troops that were there when he came into office), and plans had been announced to withdraw another 150,000 troops over the following year.
My comment stands. There is every reason to believe that Nixon fully intended to disengage from the start, and his policies aimed at doing so while achieving his other strategic goals.
Cheers,
Ben
I have come to believe that idealism without discipline is a quick road to disaster, while discipline without idealism is pointless. -- Aaron Ward (my brother)