Moscow has denied allegations by Sofia that Russian military aircraft with transponders turned off have flown in Bulgaria’s zone of responsibility. “These are provocations and jets are ready to intercept. This is alarming, so we take preventive measures," Defense Minister Nikolay Nenchev said a few days ago in an interview for Nova TV, adding that just in the past month there were 10 such cases. “There is also lack of communication that this country has been trying to overcome," he also said. In response, a spokesman for the Russian Defense Ministry said that Russian aircraft over the Black Sea fly in neutral zones and in accordance with international rules and added that the Russian Ministry had not received a letter of protest from the Bulgarian side.