Ukraine's Prime Minister Arseny Yatseniuk (R) accompanied by Defence Minister Stepan Poltorak (C) and Vice Admiral James Foggo, (L back) commander of U.S. 6th Fleet and commander of NATO's naval striking and support forces, visits the USS destroyer Donald Cook during the opening ceremony of Sea Breeze 2015 military drill in the Black Sea port of Odessa, Ukraine, September 1, 2015. REUTERS/Andrew Kravchenko/Pool