NATO troops from around the world marked an Arctic military exercise by taking dozens of selfies.
Nato announces Awacs flights over Poland and Romania to monitor the crisis in Ukraine, as 200 troops take over a naval base in Crimea.
In a rare interview, ITV International Correspondent John Irvine spoke to Taliban veteran Agha Jan Motasim about Afghanistan's future.
Russia's annexation of Crimea was partly influenced by Nato enlargement in the Black Sea region, Vladimir Putin has said.
The Russian President said the decision to beef up Nato's presence in eastern Europe had meant Russia was "forced to respond".
It would be "an historic mistake" for Russia to send its forces over Ukraine's eastern border, Nato's secretary general has warned.
Anders Fogh Rasmussen also told ITV News Europe Editor James Mates that the military alliance would do all it could to protect members if they are attacked by Russia.
NATO Sec Gen @andersfoghr Rasmussen confirms to me the alliance will take all steps to defend any member attacked by Russia, including war.
Rasmussen: "Our guarantee to our members is steadfast". But: "we can't continue to disarm while Rus increases its def spending". #NATO
Nato has confirmed that ambassadors have appointed former Norwegian Prime Minister Jens Stoltenberg as the next secretary-general of the Western military alliance.
The current secretary-general, Anders Fogh Rasmussen, said Mr Stoltenberg "is the right man to take over as Nato chief."
Nato countries have agreed that the former Norwegian Prime Minister Jens Stoltenberg will be the Western military alliance's next secretary-general, Reuters reports citing diplomatic sources.
A Nato source said a formal announcement could be made soon and added: "There's a consensus on his candidacy."
Mr Stoltenberg was the Norwegian Prime Minister at the time of Anders Breivik's attacks on Oslo government buildings and his mass shooting on the island of Utoya.
Nato is very concerned about a Russian military build-up on Ukraine's borders and has ensured all plans in place to defend members of the alliance, the organisation's Secretary-General Anders Fogh Rasmussen has said in a press conference.
"All Nato allies can be assured of our determination to provide effective defence," he said.
Mr Rasmussen added that the Western military alliance was discussing with Kiev how it could enhance its support for non-Nato member Ukraine.
Nato's secretary general has reportedly acknowledged that Russia's annexation of Crimea could not be reversed and spoke of how Moscow could go on to invade eastern Ukraine.
In an interview with Foreign Policy magazine, Anders Fogh Rasmussen said Russia's sudden conquest of Crimea was a "wake-up call" for the alliance.
He said: "Our concern is that Russia won't stop here. There is a clear risk that Russia will go beyond Crimea and the next goal will be the eastern provinces of Ukraine."
NATO Spokesperson Oana Lungescu has confirmed that the cyber attack on several of the organisation's websites is still ongoing.
DDoS attack on some #NATO sites ongoing but most services restored. Integrity of NATO data &systems not affected. We continue working on it
Unidentified hackers brought down several public NATO websites with cyber attacks on Saturday, the alliance said, in what appeared the latest escalation in cyberspace over growing tensions over Crimea.
A group calling itself "cyber berkut" said the attack had been carried out by patriotic Ukrainians angry over what they saw as NATO interference in their country.
The claim could not immediately be independently verified. Cyber berkut is a reference to the feared and since disbanded riot squads used by the government of ousted pro-Russian Ukrainian President Viktor Yanukovich
A number of NATO websites have been hit by cyber attacks, but they have had no impact on the military alliance's operations, a NATO spokeswoman said.
The attacks, which affected NATO's main website, came amid rising tensions over Russian forces' occupation of Ukraine's Crimea region where a referendum is to be held on Sunday.
NATO spokeswoman Oana Lungescu said on Twitter that several NATO websites have been the target of a "significant DDoS (denial of service) attack." She said there had been no operational impact and NATO experts were working to restore normal function.