Lightnizer letter to NAFTA is the first step in renegotiations
The letter says Trump wants to include new provisions on intellectual property, regulation, labor and environment. The aim is to finish a new deal before year-end.
It says they hope to clear up disputes about sugar with Mexico and lumber with Canada before the talks begin.
Earlier there was talk of FX provisions as well.
The letter sets the clock on a 90-day cooling off period, so negotiations can begin August 16.
