Greece as you know is in debt. It is in debt not because it spends too much on its population but because the banks systematically set it up to fail leaving it with an unplayable debt much like John Key will leave New Zealand.
The issue of course is that at some stage either the entire population of Greece will perish of starvation or they will revolt. The new Greek government was elected on a promise to revert the austerity measures strangling the Greek economy and renegotiate the debt or default. Preferably without having to leave the Euro.
The default of Greece is inevitable. There is no escaping that even as the government is imposing tax on cash withdrawals in order to keep up payments to the troika but if and when the consequences will be that the rest of the Euro zone will collapse with it.
And that is a big problem. Added to that by making overtures to Russia, Greece has opened the door to a potential military expansion of Russia into Europe too and that is something NATO will not allow. Thee question is not so much would NATO exert military power over Greece effectively acting like the tax collector for the banking cartel but when!