President Petro Poroshenko and Secretary General of NATO, Jens Stoltenberg, have discussed preparation for Ukraine's participation in the summit of the North Atlantic Treaty Organization (NATO) in Brussels (the Kingdom of Belgium) on July 11-12. Press service of the President of Ukraine said this in a statement, the Ukrainian News Agency reports. Poroshenko informed Stoltenberg about the developments in Donbas and noted the importance of deployment of a United Nations peacekeeping mission there. According to the report, Poroshenko and Stoltenberg called for the speediest release of all Ukrainian hostages held in Russia and in the occupied territories. Besides, Stoltenberg welcomed the adoption of the national security law. As Ukrainian News Agency earlier reported, Minister of Foreign Affairs and Trade of Hungary Peter Szijjarto says his country may block the confirmation of the provision of the status of an aspirant country of the North Atlantic Treaty Organization (NATO) to Ukraine.