KIEV—Ukraine’s international reserves are now at their lowest since early 2004, posing increasing risks for the country’s ability to service debt and steer itself out of the financial crisis.

Ukraine is living through the most severe economic and financial crisis in its modern history, hit by a deadly conflict in the country’s east. Ukraine’s currency, the hryvnia, has lost more than half its value over the past year, while the economy is set to contract for the second consecutive year in 2015.

...