"The United States is a supporter of the open door policy in welcoming new NATO members when they are prepared," Kerry said. Moreover, Kerry said that Ukraine has plenty of tasks to do in reforming its defense sector and implementing interoperability with NATO troops. "Mr. Poroshenko, your country has not yet reached a final decision on applying for NATO membership, but I want to assure you that the latest efforts to reform the defense sector relating to civilian control of the Armed Forces are highly appreciated as a sign of a democratic process and an important element for accomplishing interoperability with NATO member countries as a part of the Ukrainian intentions to expand cooperation with NATO within the framework of partnership that exists today," U.S Secretary of State noted.