NATO's secretary-general said Wednesday that Russia's intervention in Ukraine posed the most serious threat to Europe's security since the end of the Cold War and warned Moscow it would face international isolation.

"This is a wake-up call," alliance chief Anders Fogh Rasmussen said in prepared remarks. "For the Euro-Atlantic community. For NATO. And for all those committed to a Europe whole, free and at peace."

NATO allies on Sunday urged the deployment of international observers to Ukraine and said the alliance sought "to engage" with Moscow at NATO-Russia talks.

"We urge both parties to immediately seek a peaceful resolution through dialogue, through the dispatch of international observers under the auspices of the United Nations Security Council or the OSCE," said a statement issued after almost eight hours of talks between NATO's 28 ambassadors.

NATO defense ministers agreed Thursday the military alliance must now begin planning for a complete withdrawal from Afghanistan this year despite wanting to maintain a troop presence there.

With Afghan President Hamid Karzai refusing to sign a security pact with Washington to allow U.S. troops to stay after 2014, there was no prospect NATO could reach such an accord either, alliance head Anders Fogh Rasmussen said.

Three Ethiopian refugees who survived while 63 others died on a makeshift boat in the Mediterranean took the Belgian military to court Tuesday for failing to pick them up.

The three migrant workers fled Libya in March 2011 aboard an inflatable rubber boat just a month after the NATO military alliance established a no-fly zone as rebels battled to oust long-time dictator Moammar Gadhafi.

An Afghan soldier shot dead a Slovakian soldier on Tuesday, officials said, in the latest "insider attack" to shake efforts by the NATO coalition and the Afghan army to work together to defeat the Taliban insurgency.

The attack occurred outside Kandahar airfield, one of the biggest military bases in southern Afghanistan and a hotbed of the 12-year conflict with the Islamist rebels, a senior Afghan officer told Agence France Presse.

Three members of the NATO-led International Security Assistance Force were killed by a roadside bomb in southern Afghanistan Tuesday, ISAF said in a statement.

A spokesman declined to give any further details about the attack, which came a day after a civilian cargo plane crashed at Bagram airfield north of Kabul, killing all seven crew members.

NATO head Anders Fogh Rasmussen welcomed Afghan President Hamid Karzai Tuesday as the alliance prepares for a difficult withdrawal from Afghanistan in 2014 after years of fighting the Taliban.

NATO forces in Afghanistan are steadily "moving from combat to support," Rasmussen said, promising that the alliance would stand by the country through to 2014 and beyond, when it will take up a military training mission.

The NATO-led military force in Afghanistan will no longer publish statistics on Taliban insurgent attacks, the coalition announced Tuesday, a week after admitting some of its records were incorrect.

Officials have expressed regret that a reported seven percent decrease in "enemy-initiated attacks" in 2012 was wrong and said that attacks were roughly the same as 2011.

The commander of U.S.-led forces in Afghanistan said Sunday he would comply with President Hamid Karzai's order banning Afghan security forces from seeking NATO air support.

Karzai said on Saturday that he would issue a decree ordering an end to local security forces calling in NATO air strikes amid new tensions over civilian casualties caused by such attacks.

The European Union voiced "serious concern" Friday over Iran's decision to install more modern equipment at its Natanz nuclear plant, saying it would be in "clear violation" of its international obligations.

"We have learned with serious concern that Iran has informed the IAEA about its intention to install advanced centrifuges of the type IR2m at the Fuel Enrichment Plant at Natanz," said a spokeswoman for EU foreign policy chief Catherine Ashton.