NATO leaders have begun a key summit in Polish capital Warsaw to bulk up European defence against a perceived Russian threat to Baltic states and Poland.
Al Jazeera: NATO leaders discuss perceived Russian threats
US President Barack Obama (R), US Secretary of State John Kerry (L) and White House National Security Advisor Susan Rice (C) are seen before the meeting of heads of state of the North Atlantic Council (NAC) taking place during a NATO summit on July 8, 2016 in Warsaw, Poland.
