 Russia improves air defense. F-16s are less useful now. American F-16 fighter jets which Ukraine's partners promise to deliver at the beginning of next year may now be less effective as the Russians have improved their anti-aircraft defense. According to the Chief of the Armed Forces of Ukraine, Valery Zaloznyi in an interview with the Economist, Zaloznyi suggests that the F-16 fighter jets set to arrive in Ukraine next year may be less useful, in part because Russia has upgraded its anti-aircraft defenses. According to him, the experimental version of the S-400 missile system, which the Russians have modernized, can now reach for instance the outskirts of the city of Nipro. Earlier, Russian Defense Minister Sergei Shoigu claimed that the entire fleet of F-16 warplanes pledged to Kiev by Western donors could be destroyed in less than three weeks. He based his claim on the high rate of success shown by Russian air defenses in shooting down Ukrainian military aircraft last month. Speaking at a ministerial meeting, Shoigu praised Russian forces for conducting over 1,400 successful intercepts in October. He said the figure included 37 Ukrainian planes, almost twice the number of F-16s that foreign nations intended to give to Kiev. If our air defense forces work this way, the F-16 fleet amounts to roughly 20 days of work.