Are Greece's tanks purchases for the oppression of the population?

At the moment when it has been widely expected Greece would announce it had run out of money, we learn instead that it has just committed to spend maybe over a billion euros for 4OO renovated tanks from the USA, read here.

I reported this strange matter just before making my way to bed last evening and pondered during the early hours whether or not the country could be expecting some kind of immediate invasion. Reading the online IHT, now irritatingly arriving as the global edition of the NYT, this morning my conclusion that such an invasion seemed unlikely (other perhaps than from Turkey,) was borne out by this article, linked here, titled "How Greece could escape the Euro" from which I quote this paragraph:

But, of course, there is a way out. It would be messy, and perhaps disastrous. But no one is going to send an army to Athens to force it to keep the Euro.

Precisely, so what will the 400 tanks be used for? Is the EU about to make the final transition from putative Popperian tyranny, to the full-blown real thing?