Adem Altan / AFP - Getty Images
A Free Syrian Army soldier rips a portrait of President Bashar Assad at the Bab Al-Salam border crossing to Turkey on Sunday.
By NBC News staff and wire services
Updated 11:05 a.m. ET: The Syrian government threatened Monday to use its chemical and biological weapons in the event the country faced foreign intervention, marking the first time Bashar Assad’s regime has acknowledged it possesses weapons of mass destruction.
Foreign Ministry spokesman Jihad Makdissi stressed, however, that Damascus would not use its unconventional arms against its own citizens. The announcement comes as Syria faces international isolation, a tenacious rebellion that has left at least 19,000 people dead and threats by Israel to attack to prevent such weapons from falling into rebel hands.
Assad's forces have launched fierce counter-offensives, reflecting his determination to hold on to power even at great cost and he has dismissed an Arab offer to grant him a safe exit in return for a swift step down.
"Any chemical or bacterial weapons will never be used ... during the crisis in Syria regardless of the developments," Makdissi, speaking in English, said.
"These weapons are stored and secured by Syrian military forces and under its direct supervision and will never be used unless Syria faces external aggression,” he added.
A first? Helicopter gunships bombard Syrian capital
Damascus has not signed a 1992 international convention that bans the use, production or stockpiling of chemical weapons, but officials in the past have denied that it had any stockpiles.
As violence escalates in Syria, insurgents have said they fear Assad's forces will resort to non-conventional weapons as they seek to claw back rebel gains across the country.
Government troops launched an offensive against opposition forces in Syria days after rebels killed some of President Assad's top deputies. NBC's Lester Holt reports.
Syria's decision to reveal the long suspected existence of its chemical weapons suggests a desperate regime deeply shaken by an increasingly bold revolt that has scored a string of successes in the past week, including a stunning bomb attack that killed four high-level security officials, the capture of several border crossings and sustained offensives on the regime strongholds of the capital Damascus and the northern city of Aleppo, the country’s most populous city.
Syria is believed to have nerve agents as well as mustard gas, Scud missiles capable of delivering these lethal chemicals and a variety of advanced conventional arms, including anti-tank rockets and late-model portable anti-aircraft missiles.
A senior U.S. intelligence official told The Associated Press on Friday the Syrians have moved chemical weapons material from the country's north, where the fighting was fiercest, apparently to both secure it, and to consolidate it, which U.S. officials considered a responsible step.
But there has also been a rise in activity at the installations, so the U.S. intelligence community is intensifying its monitoring efforts to track the weapons and try to figure out whether the Syrians are trying to use them, the official told the AP on condition of anonymity to discuss the still-evolving investigation.
NYT: Both sides claim progress as Syrian violence continues
Syria's uprising began in March 2011 when the government violently tried to quash protests calling for political reform. As dissent spread and the death toll rose, scores of rebel groups formed to fight government troops, and the conflict evolved into a civil war.
Threat from Israel
Western countries and Israel have also expressed fears that chemical weapons could fall into the hands of militant groups as Assad's authority erodes.
On Sunday, Israeli Prime Minister Benjamin Netanyahu said he feared that chaos following Assad's fall could allow Hezbollah, which seeks Israel's destruction, to access Syria's chemical arsenal.
Netanyahu told Fox News Sunday that "this is something we'll have to act to stop if the need arises."
No evidence has emerged of Hezbollah involvement in Syria's unrest.
Two more Syrian generals flee into Turkey
Defying Arab foreign ministers who on Sunday offered Assad a "safe exit" if he stepped down swiftly, the Syrian leader has waged a counter-attack in the capital to defeat rebels district by district.
Arab League ministers meeting in Doha urged the opposition and the rebel Free Syrian Army to form a transitional government, Qatari Prime Minister Sheikh Hamad bin Jassim al-Thani told a news conference in Doha.
Makdissi condemned calls for Assad to step down during a meeting of Arab foreign ministers in Qatar over the weekend, calling it a "flagrant intervention" in Syria's internal affairs.
Complete international news coverage from NBCNews.com
Fighting in Aleppo
On Monday, the army shelled rebel forces in Aleppo and stormed the southern Damascus neighborhood of Nahr Aisha, breaking into shops and houses and burning some of them, activists said.
Assad's forces have reasserted control over several Damascus areas since they seized back the central Midan district on Friday, following a devastating bomb attack that killed four of Assad's top security officials.
Government forces have lost ground outside cities, ceding control of four border posts on the Turkish and Iraqi borders.
In Aleppo, activists said residents were fleeing the rebel-held districts of Al-Haideriya, Hanano and Sakhour after army shelling and clashes between rebels and government forces.
The fighting in Damascus, Aleppo and the eastern city of Deir al-Zor has been some of the fiercest yet and showed Assad's determination to avenge last week’s bomb attack.
NBC's Ayman Mohyeldin answers your questions about Syria
Fighting continued for a fifth day near key government installations, indicating that Syrian President Bashar al-Assad's control is faltering. As the opposition advances, Russia and China still refuse to support a resolution calling for tougher sanctions. NBC's Ayman Mohyeldin reports.
Bashar Assad's father, Hafez Assad, seized power in a 1970 coup and ruled for three decades until his death. Originally an Air Force officer and member of the Syrian Baath Party, Hafez al-Assad gradually introduced Alawite rule into every sector of Syrian government and society.
Activists: At least 20 men executed
In another development, government forces executed at least 20 men, aged approximately 20 to 30, activists said by phone from Mezzeh on Sunday.
"Most had bullet holes, one with as many as 18. Three had their hands tied behind their back. Some of the men were in their pajamas. Several had their legs broken or fingers missing. Others were stabbed with knifes," Bashir al-Kheir, one of the activists, told Reuters.
Analysts: Russia will be big loser if Assad falls
Opposition and rebel sources have also told Reuters the guerrilla fighters in the capital may lack the supply lines to remain there for long and may have to make tactical withdrawals.
The neighborhood of Barzeh, one of three northern areas hit by helicopter fire, was overrun by troops commanded by President Assad's brother, Maher al-Assad, 41, who is widely seen as the muscle maintaining the Assad’s rule.
Maher's role has become more crucial since Assad's defense and intelligence ministers, a top general and his powerful brother-in-law were killed by the bomb on Wednesday, part of an assault by rebels seeking to turn the tables in a revolt inspired by Arab Spring uprisings in Tunisia, Libya and Egypt.
Syrian rebels seize border post after fierce battle
Assad has not spoken in public since the bombing, but the Israeli military said it believed he was still in Damascus and retained the loyalty of his armed forces.
Regional and Western powers fear the conflict might become a full-blown sectarian war that could spill across borders, but have yet to find a coherent strategy to prevent that outcome.
NBC News staff, The Associated Press and Reuters contributed to this report.
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