Ethnic Albanian rebels attacked a 13th century Orthodox Christian monastery Tuesday, damaging the building and placing a severe strain on a fragile cease-fire that is a key requirement for NATO deployment in Macedonia.

The insurgents set off a 3 a.m. blast that caused "major damage" to the Sveti Atanasi monastery in the town of Lesok, the government said. Ethnic Albanian rebels began launching assaults last month on the village, which is just outside Tetovo, Macedonia's second-largest city.

"This is barbarism," said Antonio Milososki, the Macedonian government spokesman. The ethnic Albanians are Muslim, while the country's majority are Orthodox Christian Slavs.

The blast and other sporadic cease-fire violations come at a time when NATO troops are trying to determine if it is peaceful enough here to fan out and collect weapons from ethnic Albanian rebels.

The rebels launched their insurgency six months ago, claiming they were fighting for more rights for ethnic Albanians, who make up as much as one-third of the country's population of 2 million.

The Macedonian government says the insurgents want to capture territory and create their own state.

Dozens of people were killed and thousands were displaced before ethnic Albanian and Macedonian leaders accepted a peace deal. Under the agreement, which grants ethnic Albanians more rights, NATO troops will move in to disarm the rebels.

NATO has said it will deploy a 3,500-member, British-led force to Macedonia when it is confident that the cease-fire is viable. No one is really offering a definition of just how much fighting NATO is willing to endure and still claim a cease-fire is holding.

To help determine if the time is right, NATO's supreme commander in Europe, U.S. Gen. Joseph Ralston, met Monday with the country's top officials and senior military leaders. He will report to the alliance's ruling council Tuesday and advise them whether to give the go-ahead for full deployment.

NATO officials said it was unlikely the North Atlantic Council, made up of ambassadors from each of alliance's 19 member nations, will decide on the deployment Tuesday. More likely, they said, the council will discuss the findings and decide later in the week.

The council's next regularly scheduled meeting is Wednesday.

Ralston's visit came as an advance team moved into the countryside to make contact with ethnic Albanian rebels.

The British liaison team from the 16 Air Assault Brigade traveled to Nikustak, a rebel-held village along the front line about 10 miles northeast of the capital, Skopje. The team was meeting with local rebel commanders to discuss details of how the British-led weapons collection mission, dubbed Operation Essential Harvest, would work.

Even if NATO decides to move in, they'll find it hard to persuade those under attack that lasting peace is achievable.