Ukrainian Prime Minister Arseniy Yatsenyuk in Kiev, Ukraine, this month. (Sergey Dolzhenko/European Pressphoto Agency)

IN THE past several months, Ukraine’s freely elected government has taken dramatic steps to reform its economy, fight corruption and rebuild democratic institutions. It has imposed painful austerity on average Ukrainians, stripped oligarchs of political and economic privileges and rewritten laws to encourage free enterprise and foreign investment. It has done all this even while fighting a low-grade war against Russia, which has deployed an estimated 10,000 troops to eastern Ukraine and, with its local proxies, attacks Ukrainian forces on a near-daily basis.

Ukrainian leaders such as Prime Minister Arseniy Yatsenyuk, who visited Washington this week, see themselves as fighting on the front line in defense of Western democracy against Vladimir Putin’s imperialist autocracy. “This is about the core values of the free world,” he told us. “If we fail, this will be a failure for the entire free world.”

In spite of the government’s exertions, the odds of a Ukrainian collapse remain alarmingly high. In addition to the ongoing Russian-led military assaults, waged in blatant violation of a peace deal Moscow agreed to in February, Mr. Yatsenyuk’s government is struggling to meet staggering financial obligations. Private creditors, including the U.S.-based Franklin Templeton firm, are refusing to cooperate with a debt restructuring, sanctioned by the International Monetary Fund, that is needed to save the country $15 billion over four years.

The United States and European Union have, meanwhile, provided only paltry amounts of help, including $3 billion in U.S. loan guarantees spread over two years. While leaders of the Group of Seven nations agreed at a summit meeting this week to continue sanctions against Russia until it implemented the peace terms to which it agreed, the Obama administration and its European allies continue to deny Ukraine the financial support it desperately needs — not to mention the defensive weapons it has repeatedly requested.

Even symbolic measures of political support have been lacking. While Japanese Prime Minister Shinzo Abe visited Kiev last weekend and promised more aid, President Obama, who, like Mr. Abe, was in Germany for the G-7 meeting, has not visited Ukraine.

Mr. Yatsenyuk said he renewed his request for U.S. military aid in meetings at the White House and in Congress, which already passed with a large bipartisan majority a bill authorizing arms deliveries. To save Ukraine, he said, “you have to stop the war. To stop the war you have to undertake all efforts, including diplomatic and military. We accept that there is no military solution. But there is no way to deter Russia rather than to have a strong and effective Ukrainian military.”

Mr. Yatsenyuk found some support from Treasury Secretary Jacob Lew, who “emphasized the continued commitment of the United States and the international community to provide Ukraine with the financial support it needs,” according to a statement. A group of senators the Ukrainian leader met, including Minority Whip Richard J. Durbin (D-Ill.), endorsed his request for military aid — an appeal that previously has been supported by the secretaries of state and defense.

What’s missing is a decision by Mr. Obama to make the defense of Ukraine a priority. The president has ceded leadership on the issue to Germany and France and overridden those in his administration and Congress who support arms deliveries. In dispatching Secretary of State John F. Kerry to meet Mr. Putin last month, he appeared more intent on obtaining the Russian ruler’s cooperation on Iran than in stopping his ongoing aggression.

A stronger U.S. commitment to Ukraine will not guarantee its success. But Mr. Obama’s lukewarm support risks a catastrophic failure for the cause of Western democracy.