Why bother with air defense shields like Russia when terrorists can simply smuggle nuclear warheads into your territory? I know they don’t have nuclear warheads yet, but it takes only about 2-6 years to make your first fission bomb without prior experience and with current access to the public knowledge of nuclear physics. Fortunately, terrorists can’t afford that much time, because they don’t know if they are going to still exist in a few months, constantly fighting for survival. There’s simply no time for that type of research and development. US is shortsighted in fighting terrorism, because they are stepping back to save money. They believe that terrorists are not smart enough to do nuclear physics, because even the smartest Iranians among the people of the Middle East couldn’t make their first nuclear bomb after decades of effort, a fact assuring enough for Americans only. You can never stop fighting terrorism, because once terrorists can start breathing, they will begin their own research programs to make deadly weapons. Russia is stepping in, leaving little room for terrorists to invest in their long-term security and prosperity. US wants to watch Russia bleed as American troops did in the past and gloat over their casualties in the Middle East, a perfect role model of leadership as anyone would say.
That’s beside the point, because once the impenetrable Russian air defense shields are ready, Americans will start behaving like terrorists, building their special forces and fast response tactical troops to deploy nuclear weaponry using unconventional means. Simply put, they will start smuggling. Nothing is too lowly or too dirty for Americans, as is evidenced by the documented past activities of CIA. They do everything, including drugs, prostitution, smuggling and anything criminal you name. Plus, they are amazingly good at it. So, what is an air defense shield for? Easy. Russia has enough natural resources to maintain a self-sustainable economy for the next few decades, if not centuries. Remember that Russia is twice the size of America? That makes it easy for them to achieve economic independence. In other words, they will simply cut off all incoming traffic into Russia, making smuggling literally impossible to achieve. Even if they do need imports, they can also start building remote ports like the one in the South China Sea. If a nuclear warhead explodes there, it will only kill a few hundred lives and evaporate a few billion dollars, instead of a few million lives and a few trillion dollars. Damages can be contained easily.
So, yes, Russia does need impenetrable air defense shields, so does everyone else on the planet Earth. It makes sense.