Tensions are rising between the United States and its Western allies over Ukraine’s deteriorating economy, as American officials increasingly prod the European Union to ramp up financial assistance to the war-torn country. On several occasions this week during meetings of global financial leaders in Washington, Treasury Secretary Janet L. Yellen called on her international counterparts to accelerate both the speed and amount of money going to Ukraine. New projections from the World Bank last week suggest that Ukraine’s economy will contract by 35 percent this year, and the country’s financial officials say inflation could hit 40 percent early next year...