Four Air Guard F-15C Eagles are conducting joint air policing over Bulgaria this week. The aircraft from the Massachusetts Air National Guard’s 104th Fighter Wing and California Air National Guard’s 144th Fighter Wing along with Bulgarian MiG-29s are carrying out the the first ever joint NATO air policing mission in the Eastern European country, according to a 52nd Fighter Wing release. About 75 airmen from the 194th Expeditionary Fighter Squadron, which is forward deployed to Romania in support of a theatre security package, are supporting the mission that ends Friday. Former US Air Forces in Europe-Air Forces Africa Commander Gen. Frank Gorenc said last year the scope of the air policing mission in Europe has expanded significantly following Russia’s 2014 invasion of Crimea. The Bulgarian parliament approved the joint patrolling of its borders in February 2016. “It’s important that we are standing side-by-side with our NATO allies,” said California ANG Lt. Col. Cesar Gonzalez, commander of the 194th EFS aircraft maintenance, according to the release.