Along with the radar enhancements (which may or may not be delivered to foreign customers), Russia has a formidable integrated air defense system even though the size of its truly modern aircraft fleet is quite small compared to the United States and NATO. Russia lost a decade in the arms race when it had no money to develop and build new aircraft, and its economy today barely supports acquisition of effective numbers of new equipment. Indeed, one of the reasons Russia developed its air defenses along with wanting to counter US stealth aircraft and cruise missiles is because it could not afford a big fleet of modern fighter aircraft. (The US administration and Congress should pay close attention to Russia’s limited offensive capabilities, not too often done these days of anti-Russian hysteria in Washington.)
The invasion was a ghastly failure for the Russians, a setback which was followed by considerable German advances in the following year, including the capture of the Polish city of Warsaw . However, the crisis caused in the German High Command by the unexpected Russian advance forced the sending of 2 corps and a cavalry division from the Western Front as part of the new 9th Army in order to support the attack on the Russians. These additional forces did not arrive in time for the twin battles, as Ludendorff predicted and, had they entered France as originally planned could have been tremendously helpful to the precarious situation in the West. In the head of French Intelligence Colonel Dupont's words, "their debacle was one of the elements of our victory."