Just when you thought oil and food prices, the property price collapse and credit squeeze were all you had to worry about ...

You'd forgotten about NATO v WARSAW PACT. (aka USA v Russia)

There's another problem with a border dispute within an old Soviet block satellite state. Georgia.

After years of conflict, war, attrocities, death and hundreds of thousands innocent civilians made homeless in the old Yugoslavian area. The area is beginning to stabalise and more natural ethnic rather than enforced political borders have been established.

Now we have similar problems in Georgia which contains the areas of South Ossetia, Abkhazia, Ajaria all wish to separate from Georgia.
Of course Georgia's politicians and Generals don't want to lose territories, infrastructure, ports, raw materials, tax payers, regiments and bases ... influence and power.

With a large Russian speaking population and trade connections with Russia in these breakaway regions. The separatists have been supported by Russia in their efforts to break up Georgia. Russia don't want Georgia to join NATO as they see the protection Georgia would get through NATO membership would weaken the influence that they have on Georgia just by being a superpower with a common border.
Interceptor missiles based in Georgia would be seen as a serious shift in the balance of power in the region.

Which brings us to ...

Poland has agreed a deal with the US to put Interceptor missiles on Polish soil, said to be placed there as it's the perfect place to intercept missiles from 'Rogue states' before they reach European airspace and targets.
Russia sees this as a serious threat to the balance of power in the area and has said it will increase the number of ballistic missiles targetting Poland to counter this threat.

So why the fuss about a defence shield ..

The interceptor is built in two parts. The first part is a three stage booster that lifts the second part the 'nose cone' into space. The nose cone contains no explosives, it's a bullet. From the edge of space it is targeted to intercept the incoming missile and the booster separates sending the 'bullet' to crash into and thus destroy it's target.

Tests have shown it works.

If it works 100% it makes an equal amount of Russian missiles ineffective, thus the balance of first strike threat is shifted. Which will lead to initially more Russian missiles being built and finally a Russian defence shield developing. The arms race starts again. This time with interceptors. If enough interceptors are built and deployed eventually we'll end up in world where the building and firing long range missiles is useless.
Unfortunately until this balance in the arms balance is corrected we're set to go through another Cold War, with mis-trust and postulating prevalent by both camps.

 This is a video showing a test firing of a Japanese ship based interceptor.