"Alliance aircraft routinely operate together in the Black Sea region in order to hone communication skills and enhance interoperability for future missions," Brigadier General Christoph Pliet, NATO Deputy Chief of Staff Operations, said in a statement.
US aircraft, deployed to Spangdahlem airbase in Germany, flew on Monday to Bulgaria where they linked with Dutch fighters, based in Bulgaria under NATO's Air Policing mission, the statement noted.
Bulgaria's Graf Ignatievo airfield allows US fighters to increase their operating range over the Black Sea, the statement added.