US military force in the US-South Korea joint drill in Gunsan city, South Korea                  on April 20th, 2017 (Photo: AFP/VNA)

A 10-day NATO drill began in Bulgaria on Tuesday involving 25,000 soldiers from 22 countries. The US-led “Saber Guardian 17” exercise will also take place on Thursday in Hungary and Romania’s Mihail Kogalniceanu airbase close to the Black Sea. Consisting of 18 specialized exercises, the drill aims to improve coordination among allied countries.