Percent of GDP is a poor measure of military effectiveness. We could boost our spending by buying dozens of stealth fighters and keeping them on the ground except to parade around at photo-shoots... LIKE THE U.S. DOES... but it wouldn't improve the effectiveness of our military.

It's like Healthcare. Americans spend 2.5x the OECD average on healthcare, but Americans have a lower life expectancy, fewer doctors, and fewer hospital beds per capita than the OECD average. Spending does not correlate to effectiveness, especially when the U.S. is involved.