Tsvetanov also successfully developed bilateral police cooperation with Bulgaria's NATO and EU partners throughout this time. In 2013, the US Drug Enforcement Agency – DEA opened an office in Sofia. Personally, the director of the agency, Michelle Lionhart, gives a high assessment of Tsvetanov's work:"Your dedication to your work has undoubtedly contributed to the rule of law and made both the Republic of Bulgaria and the United States a safer place for the citizens of both countries".
