Speaking in Brussels, Frank-Walter Steinmeier also told reporters on Wednesday that it was still unclear what the future relationship between Russia and the United States would be, Reuters reports.

"In contrast to some views I have seen, I personally think it is completely open as to (what kind of) relationship develops between the United States and Russia," he told reporters, adding pressing the 'reset button' had not got any easier in the last eight years given the range of new conflicts.

Read alsoInternational community should maintain pressure on Russia until full Minsk implementation – StoltenbergAs UNIAN reported earlier, U.S. Deputy Secretary of Defense Bob Work said following his meeting with Ukraine's deputy prime minister Ivanna Klympush-Tsyntsadze that Ukraine needed to "maintain momentum on defense reforms" to help Ukraine better provide for its own security and make its defense enterprise more effective and efficient.

At the same time, he said that the fiscal year 2017 National Defense Authorization Act offered a promising signal that security cooperation efforts could continue in the new year.