Over 10 months of fighting in eastern Ukraine, the West has slammed Russian President Vladimir Putin for supplying arms to the conflict zone.
If U.S. President Barack Obama arms Ukraine, Washington will squander the moral high ground and bloody the United States' conscience. It would also be a betrayal of Europe's interests.
U.S. officials say giving lethal defensive military equipment to the Ukrainian army will enable Kiev to halt the advances of separatists armed by Russia. They say the policy will promote peace by raising the cost of fighting for Putin and forcing him to negotiate.
Russia is more likely to see the decision as a declaration of war and escalate the conflict.
U.S. aid is a propaganda gift to the Kremlin, allowing it to bring its covert war out of the shadows. Putin controls the country's key media, and Russians would support any fight against U.S. hegemony, whatever the economic and human cost.
The Kremlin has already shown that it will send its troops to die for its policy in Ukraine.
But the West is not ready to shed blood for Ukraine. Violence plays into Russia's hands because the Kremlin is the only party prepared to use it.
Faced with Russian escalation, the United States would either have to back down and lose credibility or — more likely — commit to funding a proxy war on the European continent.
This would cost thousands more lives, create a continental security crisis, rupture Russia-EU ties and damage Europe's economy further through sanctions and tightening of borders.
Vice President Joe Biden and Senator John McCain can stand at lecterns and imply that European leaders are weak-willed and soft on principles. But they represent the United States, which is half a world away from the war zone and has minimal trade with Russia.
The European Union stands to lose tens of thousands of jobs and gain a war on its borders.
If the United States and Europe want to take a principled stance they should employ means that they are prepared to use — economic, financial and diplomatic.
U.S. officials say they are defending principles of liberty and international law. Instead they are playing fast and loose with pocket change and far-away lives.