Ukraine’s $30 Billion Problem: How to Keep Fighting Without Foreign Aid

Ukraine will run out of money within months and be forced to take painful economic measures to keep the government running if aid from the U.S. or Europe doesn’t come through, according to economists and Ukrainian officials.

The U.S. and the European Union, Ukraine’s largest financial backers, have promised Kyiv billions of dollars in new financial and military aid. But pledges from both have been upended by infighting in Washington and in Brussels. While political leaders insist those aid packages will pass eventually, timing is critical for Ukraine.

The country faces a $40 billion-plus...