Nato supports Ukraine's territorial integrity against Russian occupation

It added that Ukrainian people have a right to determine their own future “without outside interference.”

Ukraine is not a member of Nato and the military bloc is not obliged to come to its aid.

But for their part, two Nato members, Lithuania and Poland, had called for the NAC meeting citing article 4 of the Nato treaty, saying that they themselves feel that their own “ territorial integrity, political independence or security” is under threat due to the events in Ukraine.

Some 6,000 Russian airborne and ground troops poured into the peninsula over the weekend, with reinforcements still arriving as Ukraine’s interim government put its military on high combat alert.

Ukrainian military bases in Crimea are now surrounded by Russian troops and local militia and Ukrainian soldiers are being urged to defect.

Some already have: Denys Berezovsky, who was appointed Ukraine’s Rear Admiral on Saturday by the interim government in Kiev, proclaimed his allegiance on Sunday “to the supreme commander of the autonomous republic of Crimea.”

Berezovsky told Ukrainian naval forces in the area to stand down and reject any orders from Kiev.

Meanwhile, the US conceded that Russia now has “complete operational control of the Crimean peninsula” as Western leaders try to put pressure on Moscow to withdraw troops by threatening economic and political isolation.

Russia’s G8 partners, for their part, decided to suspend an upcoming summit in Sochi in June.

“We are united in supporting Ukraine’s sovereignty and territorial integrity, and its right to choose its own future,” said the seven industrialised nations in a statement.

The leaders, representing Canada, France, Germany, Italy, Japan, the United Kingdom, the United States and the EU, said they will not engage with Russia on the summit "until the environment comes back where the G8 is able to have meaningful discussion.”

Ideas floated by US senior administration officials include kicking Russia out of the economic club, which it joined in 1998.

But excluding Russia from G8 altogether has received a lukewarm response from Germany’s foreign Minister Frank-Walter Steinmeier.

Steinmeier said the economic forum is the only one in which the West can speak directly with Russia.

“Should we really give up this unique format?”, he told German public broadcaster ARD.

Germany relies heavily on Russian natural gas produced and delivered by Russia’s state-owned Gazprom.

Putin, for his part, has justified the troop deployment on the ground to protect the lives of Russian citizens stationed in the peninsula following last week’s overthrow of Russian-backed president Viktor Yanukovych.

German Chancellor Angela Merkel told President Barack Obama by telephone on Sunday she believed Putin, a former KGB colonel, is “in another world,” while Ukraine’s interim Prime Minister Arseniy Yatsenyuk warned that the country is “on the brink of disaster.”