Recently, the Ukrainian Defense Minister Yuriy Yekhanurov made a week long visit to China. They talked a lot about military cooperation during this time. If you haven't noticed yet, Ukraine is one of China's most important partners in military cooperation. Two of the highest priority projects right now (naval aviation training and large transport) are getting a lot of help from the Ukrainians. On top of that, China also relies on Ukrainians for many of the engines used on air planes, helicopters and ships. It also has bought missiles for Russian built flankers from the Ukrainians and worked with the Ukrainians to upgrade weaponry bought from Russia. On this trip, the Ukrainians also indicated that Ukraine might purchase L-15 and seek for shipbuilding help from China. Clearly, this military cooperation relationship will continue for sometime. We also know that there are many in Ukraine and US calling for including Ukraine in NATO. So, exactly how will joining NATO affect China's military cooperation with Ukraine?
It was speculated that after the orange revolution in Ukraine, US pressured Ukraine to limit its military cooperation with China. Although, that doesn't seem to have been true. Turkey is another NATO country that have had some military cooperation with China. We know that it entered into joint development relationships with China for WS-1B and B-611. However in both cases, China was in effect exporting them to Turkey (I don't think Turkey contributed that much), so the Bush Administration didn't really object to them. Of course, there have also been export of minor systems from EU countries to China like Spey Engine, Skymaster radar, ship propellers, diesel engines and some other items. Due to American pressure and the improvement of Chinese hardware, dual use exports have pretty much reduced diesel engines and a possible future Z-15 military version. And due to American pressure, the support around lifting European arm embargo in 2005 basically faded. Even if the embargo gets lifted in the next 2 or 3 years, it's hard to see how much lifting embargo will even help China. Canada has also had some cooperation with China in supplying initial batch of engines for Z-10, Z-8F and Y-8. Even though there is no explicit embargo by Canada on China, it's hard to see any significant military cooperation between the two countries with US around the corner.
Generally, US pressure will force most NATO countries from exporting sensitive technology or assisting the development of advanced weaponry to China. At the same time, the availability of US weapon means that these NATO countries will likely not import anything from China either. And if Ukraine ever joins NATO, that problem would mean the end or near the end of future military cooperation between the two countries.