Ukraine Needs the U.S. to Respond to Russia

When 298 innocent people were shot out of the sky by a Russian missile 10 days ago, people everywhere finally began to understand what is at stake in Ukraine.

Half a year ago, I was not even considering becoming president of Ukraine. But like a great many Ukrainians at the time, I was disturbed that then-president Viktor Yanukovych constrained Ukraine’s future by rejecting an association agreement with the European Union, choosing a customs union with Moscow instead. Like so many of my countrymen, I believed that for Ukraine to become a modern and successful country, it needed to expand its ties with the West and end widespread corruption and abuses of power. Then, the authorities unleashed a murderous assault on demonstrators in Kiev, and Yanukovych and his partners fled to Russia, leading to Moscow’s decision to annex Crimea and support the violent separatists operating in eastern Ukraine.

Russia’s behavior has only worsened since I took office in June. Over the past several weeks, Ukraine has resisted Russian aggression and continues the fight against the Moscow-backed separatists. Russia has tested us with its transfer of cash, weapons and other equipment to the separatists and its vast anti-Western, anti-Kiev propaganda campaign, but we will not yield to its interference in Ukraine’s sovereignty or to the violence perpetuated by terrorists.

Moscow is playing a dangerously irresponsible game. My fears of the violence spiraling out of control were confirmed July 17, when the separatists used Russian missiles to shoot down Malaysia Airlines Flight 17. This attack on innocents should never have happened. Like giving a handgun to a child, Moscow permitted the transfer of a highly sophisticated surface-to-air missile system to terrorists. With such a large number of lives lost — many of them children — this was a major tragedy. Adding to the horror has been the casual desecration of the crash site by the separatists, who have blocked access by...