United Kingdom's position in NATO will remain unchanged: NATO

"The British people have decided to leave the European Union. As it defines the next chapter in its relationship with the EU, I know that the United Kingdom's position in NATO will remain unchanged. The UK will remain a strong and committed NATO Ally, and will continue to play its leading role in our Alliance," Stoltenberg  said in a statement.

"Today, as we face more instability and uncertainty, NATO is more important than ever as a platform for cooperation among European Allies, and between Europe and North America. A strong, united and determined NATO remains an essential pillar of stability in a turbulent world, and a key contributor to international peace and security," read the statement.

"The Alliance remains committed to closer cooperation with the European Union. At the Warsaw Summit in July, we will step up our cooperation, because together we are more effective in upholding our common values and keeping our nations safe," he said.

David Cameron, who fought for the remain campaign in the EU referendum and had put his neck on the line almost in his impassioned plea to voters to keep Britain in the EU, announcedon Friday to resign in three months as the British Prime Minister.

Cameron, who served as the Prime Minister for six years, spoke in a broken voice as he announced his resignation.

"....the British people have made a very clear decision to take a different path, and as such, I think the country requires fresh leadership to take it in this direction," he said reading out a statement before 10 Downing Street.

Despite a close battle, Britain has voted (52 percent) to leave the European Union in a historic referendum on Thursday as results were declared on Friday, thus severing a tie of decades and dealing a blow to the European unity.