From the monetary fortress of the European Central Bank to the pro-European duchy of Luxembourg, policy makers are beginning to air their doubts that Greece can stay in the euro.

Post-election tumult in Athens has put the once-taboo subject of an exit from the 17-country currency union on the agenda, lifting the veil on possible scenario planning afoot behind the scenes.

"If Greece decides not to stay in the euro zone, we cannot force Greece," German Finance Minister Wolfgang Schaeuble said at a conference sponsored by German broadcaster WDR in Brussels today. "They will decide whether to stay in the euro zone or not."

After 386 billion euros ($499 billion) in aid pledges for Greece, Ireland and Portugal, 214 billion euros in ECB bond purchases and another trillion euros in low-interest loans for banks, plus 17 high-level crisis summits, Greece's political chaos thrust Europe into a perilous new phase.