Syria's Foreign Ministry spokesman, Jihad Makdissi, confirmed July 23 that Syria possessed chemical and biological weapons. Makdissi pledged that Syria would never use these weapons during the ongoing crisis in the country, but he did not rule out using them against foreign aggressors.

The United States and its allies have clearly stated their intention to prevent Syria's ongoing crisis from leading to the proliferation of chemical and biological weapons. The concern is not so much that the Syrian regime would use chemical weapons in the conflict — that would invite foreign intervention and a potentially violent end to the regime. The international community's main concern is that, given the instability in the country and the military's imperative to protect key areas such as Damascus, Syria's weapons stockpiles could become vulnerable to theft. The United States and Israel worry that the weapons could fall into the hands of anti-Israeli jihadists, who would not hesitate to destabilize the region further by attacking Israel.

Syrian opposition forces will likely argue that these weapons pose a threat to them and to others, but the United States and its allies have been monitoring Syria's chemical and biological weapons arsenal using everything from unmanned aerial vehicles to human sources on the ground. Furthermore, Syrian rebels have acknowledged the importance of securing these weapons should the rebels gain power. Despite the looming threat behind Makdissi’s statement, it is unlikely that the United States and its allies will use his announcement as a pretext for foreign intervention. Syrian chemical weapons would have to appear to be falling into the hands of jihadists — a threat that does not seem imminent — to compel the United States and others to intervene.

There are two reasons Washington and its allies are ruling out intervention for now. First, there are the tactical limitations of securing Syria's arsenal. Syria is not like Libya, whose chemical weapons — which were only deliverable by plane and stored in a handful of sites — were in the process of being destroyed. Syria is believed to have between 45 and 50 chemical- and biological-weapons sites spread across its territory. The weapons contain harmful material that has been preserved and fit into devices that can effectively distribute the material against a specific target. These weapons are also deliverable by ballistic missiles, artillery and aircraft. Only a considerable air, naval and ground campaign — essentially a full invasion — could destroy or secure Syria's weapons sites.

The second reason for avoiding intervention is that the United States does not want to commit to another military campaign in the Middle East — this is why the West has not directly intervened in Syria. The decision to support the rebels was a strategy the United States adopted early in the conflict and is meant to alleviate the need for military intervention. The United States and others could have used a number of different incidents as pretexts for entering the conflict (the shooting down of a Turkish jet in June being the most recent example), but they have not done so. The public revelation that Syria has chemical and biological weapons likely won't change that.

Syria's acknowledgement that it possesses chemical and biological weapons is a way of negotiating its endgame. The United States and its allies want to make sure that the power transfer is gradual and comprehensive, with territory handed over to the opposition slowly and methodically so that weapons stockpiles can be secured and accounted for. Members of the Syrian regime would like to resolve this crisis without dying in the process. Rushed transitions of power carry increased risks of unpredictability that could prompt a proliferation of chemical and biological weapons and a bad ending for the regime and its leaders.

Syria's announcement that it possesses chemical and biological weapons was meant to remind the United States and its allies that there are risks to quickly bringing down the regime. The United States wants to make sure that a proliferation of chemical and biological weapons in Syria doesn't become the legacy of its involvement in the crisis.