Regrettably but unsurprisingly, the Crimea crisis ratcheted up Monday.
The new regime declared its independence from Ukraine following Sunday's overwhelming vote to secede and join Russia. Russian President Vladimir Putin signed a decree recognizing Crimea as "sovereign and independent." His defense ministry has declared that Ukrainian soldiers still in Crimea have until Friday to leave peacefully.
Declaring the referendum tainted and illegitimate, the United States and European Union froze assets, restricted business dealings and banned travel of a handful of Russian and Ukrainian officials they hold responsible.
These sanctions are the toughest against Russia since the Cold War, and President Barack Obama warned there could be more if Russia doesn't back down. While they are not as severe as some expected and noticeably do not target Putin, the penalties are among the options realistically available to exact some price for Russia's outrageous actions.
The West is not going to war over Crimea, however. As long as Putin is willing to accept economic pain and diplomatic isolation, Russia will annex Crimea at gunpoint.
What the U.S. and its European allies need is a strong and united strategy to deter incursions into the rest of Ukraine. Russia is reportedly massing troops on the border. In a televised address to his nation, Ukraine's acting president said that "the military threat to our state is real."
It's also not too early to think several moves ahead. The West must shore up its military support and make clear its security commitment to the Baltic states and Poland.
Wisely, the Obama administration has already started to do that. Earlier this month, it dispatched six more F-15 fighter jets to increase NATO air patrols over Estonia, Latvia and Lithuania. The U.S. also sent a dozen F-16s to Poland to take part in beefed-up training exercises. This week, Vice President Joe Biden is in the region to meet with the leaders of those countries to reinforce that important solidarity.
The West's actions will not be without cost. Russia could retaliate with sanctions of its own, and it could be less helpful to the U.S. and others in the delicate diplomacy needed to end Syria's civil war and limit Iran's nuclear program.
If Putin continues down this risky road, sanctions may not be enough to stop him. The West certainly doesn't want a direct military confrontation with Russia, or a return to the Cold War. But we cannot allow the tide of history to be reversed, either.