According to my time travelling friend John Titor:
After the UK finally left the EU in the mid 2020s, no more money was available to support ailing Nations and Germany decided to collect upon its debts giving Greece 28 days to settle in full.
Obviously this was impossible for the note impoverished country and faced with the prospect of key areas falling once more into German ownership the government did a deal Argentina instead for an undisclosed amount paid in gold and silver bullion. The result of which was that large amounts of the country became a colony.
Curiously a large amount of the bullion was already stamped with German markings dating from around 1944, naturally the Greek government made a grand show of returning this to Germany whilst mentioning repeatedly that the amount was still less than that owed by German to the Greek people for war time reparations.