U.S. Secretary of State Mike Pompeo held talks with visiting Bulgarian Foreign Minister Ekaterina Zaharieva on bilateral ties and other issues on Monday.

Pompeo and Zaharieva discussed bilateral relations, Bulgaria's military modernization plans, and energy diversification as a European energy security priority, according to a statement issued by the State Department.

The two sides also exchanged views on Iran's ballistic missile program, sanctions on Russia, and the situation of the Western Balkans.

Bulgaria, a NATO member since 2004, signed a defense cooperation agreement with the United States in 2006.

Moscow has regularly accused NATO of boosting its military presence in Eastern Europe, including Bulgaria.