Firstly, the US is not the only supplier of F-16 parts! Turkey and other countries that own US manufactured war planes, been manufacturing and purchasing spare parts from China under everyone's nose. That's why Lockheed Martin constantly lobbies the US government to take stricter actions against such offenders. Secondly, and as we have seen many times in the past, Russia is usually more than ready and happy to quickly supply any country with whatever weaponry the US stops short of supplying. Obviously the Russians do this because of the lucrativeness and most importantly to show defiance against the US. The US needs Turkey more than ever to win the never ending wars in Iraq and Afghanistan. Turkey provides strategic gateway to supply the American armies.
Policeman killed by blast in Bahrain village, interior ministry (Reuters)
from the article: U.S.: Turkey must prove its commitment to the West