A "glimmer of light" is how German Chancellor Angela Merkel described the agreement reached last week among the leaders of Ukraine, Russia, France and Germany to try to bring peace to Ukraine. It says a lot that the deal is called "Minsk II," named after the city in which it was negotiated. It is a direct followup to a failed agreement reached just five months earlier.

Minsk II is likely to work as a cease-fire, but the larger forces driving the conflict in Ukraine will remain. In particular, Russian President Vladimir Putin remains convinced that his country is under assault, that it must expand its sphere of influence and that the West will be unable to stop him from doing so.

Sixteen hours of talks between Putin, Merkel, French President Francois Hollande and Ukrainian President Petro Poroshenko yielded the agreement. It gave the combatants 70 hours to withdraw from a buffer zone before a cease-fire began. The cease-fire will ratify the separatists' control of territory seized during 10 months of fighting — at least until the end of 2015 when all sides will sign a comprehensive agreement that will fashion a permanent end to the fighting. That agreement will return rebel-held territory to the government in Kiev; in exchange, however, Ukraine will amend its constitution to allow the eastern regions more autonomy.