Not war, per se, but rather the stability the point makes more generally. It's easy to look at Mexico and see a country impoverished and rife with corruption, but the pressures put on it by NAFTA have seen it make some impressive moves over the last 30 years. It has the added benefit of reducing immigration incentives (which seem to preoccupy a lot of Americans these days).
I'm not well versed in the details of NAFTA but are you contending that one of it's main benefits was preventing a war between the US and Mexico?