The mayor of Kyiv, Ukraine, Vitali Klitschko, is sounding the alarm over the number of soldiers the country can retain as it fights to stave off Russian forces.

Klitschko said Ukraine is having “huge problems” finding enough soldiers to defend the country, as Ukrainians flee west from the war-torn region to Europe. Klitschko suggested the government should lower the age at which citizens can be enlisted in the country’s army from 25.