The head of Nato says it is responding to Russia's military intervention in Ukraine by suspending most of the military alliance's meetings with Russia and reviewing all of its co-operation with Moscow.
Nato secretary-general Anders Fogh Rasmussen said that ambassadors for Nato's 28 member states decided after a meeting with their Russian counterpart to suspend plans for a joint mission as well as all civilian and military meetings.
Rasmussen said because of Russia's military action in Ukraine's Crimean peninsula "the entire range of Nato-Russia cooperation (is) under review."
Rasmussen said the alliance will continue to meet with Moscow at the political level but insisted that halting all other cooperation "sends a very clear message to Russia".
He also said Nato decided "to intensify our partnership with Ukraine".
Meanwhile, in his first interview since taking office, Ukraine's new prime minister vigorously defended the legality of his government, but said today that Ukraine would be willing to consider granting more autonomy to the Crimea region to assuage the concerns of the province's pro-Russian population.
Prime minister Arseniy Yatsenyuk denied reports that Ukraine is seeking military assistance from the United States.
Since last weekend, Russian troops have taken control of much of the Crimea, a peninsula in the Black Sea where Russian speakers are in the majority.
Yatsenyuk, who took office last week, blamed Russian president Vladimir Putin for causing one of the sharpest international crises in Europe since the end of the Cold War - and expressed fears about further possible Russian incursions.
Asked if he was afraid that Russia might send troops to occupy other Russian-speaking areas of Ukraine, Yatsenyuk said: "Let me put it bluntly: yes, it's still a concern and Russia is to realise its responsibility and Russia is to stick to its international obligation, to stop the invasion.
"Mr president (Putin), stop this mess," said Yatsenyuk.
The prime minister, approved by parliament on February 27, also denied a report that cash-strapped Ukraine was negotiating with the United States for deployment of US missile defenses in exchange for financial help.
"This is not true," Yatsenyuk said. "We have no talks with the government of the United States of America on any kind of deployment of any military forces. The only negotiations we have is to get financial support, financial aid from the United States government in order to stabilise the economic situation in my country. It's absurd."
On Tuesday, Putin said Ukraine's current leaders had come to power as the result of an unconstitutional coup. In the interview, Yatsenyuk blamed Russia's leader for the ongoing crisis and said Putin was the one acting outside the law.
"A number of military forces of the Russian Federation are deployed in Crimea. We cannot figure out the reason why Russian boots are on Ukrainian ground. And it's crystal clear that it was ordered personally by president Putin. This is Ukrainian territory and Russia wants to grab control over Crimea. But I will underline again, we will do our best in order to regain control over Ukrainian territory. The Russian military is to be back in the barracks."
"What happened in Crimea is unconstitutional and resembles ... a coup supported by the Russian government and the Russian military," Yatsenyuk said.
"The Ukrainian government is legitimate. And let me remind Mr Putin that this government was supported by the constitutional majority of Ukrainian MPs with 371 votes. We are legitimate and we must fulfill our responsibilities. And we strongly recommend to our Russian partners to build up relations with the new Ukrainian government."
Yatsenyuk said he hadn't talked personally to Putin, "but it's in the interests of our countries to start a dialogue."
"First we need to stop the invasion and afterward we want Russia to (be) our partners, real partners and to stop this zero-sum game. It is to be a win-win game where both Ukrainian and Russian interests are considered," he said.
"So we urge the Russian government to start real talks with the new Ukrainian government and we ask Russia not to be a neighbor but to become a real partner."
Yatsenyuk, 39, is a millionaire banker who has served as the economy minister, foreign minister, and then parliament speaker. He unsuccessfully ran for president in 2010. He is viewed as a technocratic reformer and enjoys the support of the United States.
Yatsenyuk said Crimea must remain part of Ukraine, but may be granted more local powers. He said was in favor of establishing a special task force "to consider what kind of additional autonomy the Crimean Republic could get".
He said the economy of this former Soviet republic "is in a big mess" - but that the new government is taking action to improve things.
"The state treasury is empty. And due to unbelievable and unlimited corruption in my country we cannot collect revenues in order to execute our social obligations, but despite this we have a clear-cut action plan how to tackle economic problems.
"We resumed talks with the International Monetary Fund. The IMF mission is on the ground. A good gesture made by the United States government to support the state of Ukraine with one billion dollars (£600 million) of guarantees is a first sign that Ukraine could be back on track in terms of economic stability.
"But we need to move further."
In Crimea a special UN envoy cut short his mission after being threatened by 10 to 15 armed men and ordered to leave the region.
After a confrontation at a cafe, envoy Robert Serry was driven to Simferopol airport by the men and was flying to Kiev, Ukraine's capital, where he will continue his fact-finding mission, the officials said.
Before leaving Simferopol, an Associated Press reporter found Serry in the business class lounge of its airport.
"I'm safe. My visit was interrupted for reasons that I cannot understand," the Dutch diplomat said.
Last week, UN secretary-general Ban Ki-moon dispatched Serry to Kiev as a special envoy because he was the Netherlands' first ambassador to Ukraine and knows the country and many key people.
Ukrainian officials reported earlier today that Serry had been kidnapped. But Jan Eliasson, the UN deputy secretary-general, denied that. Eliasson said Serry was threatened by the armed men as he was leaving naval headquarters in Crimea, but was not abducted.
Eliasson said the men ordered Serry to leave Crimea and go to the airport. Serry refused, but he couldn't move because his car was blocked, said Eliasson.
The envoy was later seen in the cafe, as armed men in camouflage outfits stood outside. He then got into a van with the men and was taken to Simferopol airport.