ZAGREB, Croatia—The United States on Thursday delivered two Black Hawk military helicopters to Croatia, which is engaged in a mini arms race with neighboring Russian ally Serbia amid simmering tensions in the post-war Balkan region. The U.S. Embassy in Croatia’s capital, Zagreb, said the donated UH-60M multi-purpose helicopters will contribute to Croatia’s growing defense capabilities and military preparedness in support of NATO. “The Black Hawk provides capabilities across a range of possible missions, from special operations to tactical troop transport to aeromedical evacuation,” U.S. Chargé d’Affaires Mark Fleming said as the helicopters arrived on a U.S. Air Force transport plane to Zagreb. “Croatia has earned a reputation as a committed and capable NATO ally, and the introduction of Black Hawks will further boost the capacities of the Croatian Armed Forces,” Fleming said in the statement. Defense Minister Mario Banozic thanked the U.S. for the donation. “It represents evidence of strong, …