TRIPOLI, Lebanon &

Military aid from the United States and Arab allies began arriving Friday after Washington said it was rushing supplies to the Lebanese army battling al-Qaida-inspired militants barricaded inside a Palestinian refugee camp in the country's north.




Sporadic gunfire exchanges early Friday punctured the lull in the fighting as the Lebanese army continued to build up around the Nahr el-Bared refugee camp near the port city of Tripoli.




The move appeared to be either a preparation to storm the camp &

a maze of narrow streets and tightly packed homes where hundreds of Fatah Islam militants are holed up &

or a tightening of the siege to force them to surrender. Thousands of Palestinian refugees are trapped inside.




A deputy Fatah Islam leader threatened more violence if the army attacks Nahr el-Bared. Abu Hureira told the pan-Arab Al Hayat daily by telephone that "sleeper cells" in other Palestinian camps and elsewhere in Lebanon were awaiting word for a "violent response."




Fatah Islam's confrontation has generated Internet support messages from other Islamic militants. The Washington-based SITE Institute, which monitors militant trafficking, said Friday it had obtained a 7-minute video allegedly from a group calling itself al-Qaida in al-Sham &

an Arabic name for the region of Syria, Lebanon and Jordan &

warning against continued bombardment of Nahr el-Bared.




If the shelling continues, "Christians in Lebanon will suffer and tourism and trade will also suffer," said the obscure group, which is not known to have carried out any attacks. Christians are a large minority in Lebanon.




Although U.S. officials said the military aid to Lebanon had been agreed to before the fighting broke out this week, the speedy shipment Friday marked the first tangible U.S. backing of the Lebanese authorities' fight with the militants.




early afternoon Friday, a total of five military transport planes landed at the Beirut airport, including one from the U.S. Air Force, two from the Emirates' air force and two Royal Jordanian Air Force planes. Both Jordan and Emirates are close U.S. allies.




U.S. military assistance, limited during Syria's control of Lebanon until 2005, increased after last year's summer war between Lebanese Hezbollah militants and Israel.




Hoping that a boosted army could eventually disarm Hezbollah, the U.S. has pledged $40 million in military aid. Lebanon's 70,000-strong army is underarmed and overstretched, with army leaders complaining of a lack of heavy armor, anti-aircraft missiles and the absence of an air force.




The fighting in Lebanon, which erupted Sunday when police raided suspected Fatah Islam hideouts in Tripoli while searching for men wanted in a bank robbery, has killed some 50 combatants and many civilians so far.




Prime Minister Fuad Saniora said Thursday that Fatah Islam was "a terrorist organization ... attempting to ride on the suffering and the struggle of the Palestinian people."




Saniora said his government "will work to root out and strike at terrorism" but insisted it has no quarrel with the 400,000 Palestinian refugees in the country. Under a 1969 agreement, Lebanese military stays out of the camps that are run by the Palestinians.




Fatah Islam spokesman Abu Salim Taha repeated Thursday that the group would never surrender but "fight until ... the last drop of blood and the last bullet."




Storming the Nahr el-Bared camp could mean rough urban fighting for Lebanese troops and further death and destruction for the civilians inside. It could also spark unrest in Lebanon's 11 other Palestinian refugee camps. Palestinian factions have dissociated themselves from Fatah Islam but are angry over army bombardments that have partially destroyed Nahr el-Bared.




Three bombs have exploded in the Beirut area since Sunday, killing one woman and injuring about 20. Fatah Islam has denied responsibility for the bombings.




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Associated Press writers Lolita Baldor in Washington and Sam F. Ghattas in Beirut contributed to this report.