Since before the beginning of the State of Israel, Israel has always made it a point to do whatever it needs to do in order to have the military capabilities it needs to fight off it’s enemies. And it has always had to make do with less than it really needed. 

Even today when the State of Israel is an economic wonder, it still needs to be able to make modifications on the most sophisticated equipment that it purchases from American companies. It is that edge that often makes the entire difference.   

Even when Israel has strong friends in the Oval Office, it can never rely on that situation continuing for more than a few years.