WASHINGTON (CNN) -- The Pentagon has consistently updated its options for using the U.S. military in Syria, as conditions on the ground have changed. But these are only options at this point, and senior military officials say President Barack Obama has not yet asked to see a potential plan of action.
NATO commander Adm. James Stavridis said Tuesday, "The Syrian situation continues to become worse and worse and worse."
Stavridis said several NATO countries are working on contingency plans for military action in Syria, including imposing a no-fly zone, providing lethal military assistance to rebel groups and imposing an arms embargo on the Syrian government. Stavridis said these are being discussed on an individual level among these nations, and have not been brought up to NATO as a whole.
A senior U.S. official says American military commanders continue to advocate strongly for a diplomatic solution rather than a military strike. The top U.S. military officer said this week that Syria posed the most complex set of issues he could conceive. Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey said, "About six months ago we had a very opaque understanding of the opposition. And now I would say it's even more opaque."
Dempsey has said he favored arming the rebels last year, when the Pentagon had discussions on the subject with the White House. But Obama decided to limit U.S. assistance to nonlethal aid, and Dempsey now seems more adverse to arming groups that may be influenced by extremist elements: "I don't think at this point I can see a military option that would create an understandable outcome. And until I do, it would be my advice to proceed cautiously."
Stavridis said there has been consideration of targeting Syria's air defenses. NATO has installed Patriot missile batteries in Turkey, near its border with Syria. Stavridis said those Patriots could be aimed to potentially shoot down Syria's aircraft. But Turkey only allowed the missile batteries to be placed there for defensive purposes, and NATO nations would have to agree to use them for offensive strikes against Syria. Stavridis indicated that is not something under immediate consideration. U.S. military and Intelligence officials have been consulting with Israel, Jordan and Turkey about potential options should Bashar al-Assad launch a chemical attack on the Syrian people.
U.S. officials say the military has enough firepower in the region to take action against Syria, if needed. That includes fighter jets and bombers, spread out across land bases in the Middle East and nearby aircraft carriers at sea. The Navy also has warships equipped with precision-guided Tomahawk missiles, which could be used to strike chemical weapons supplies. But the officials say there is a danger that any strike would release the chemical agents into the air around civilian populations in Syria. Other options include bombing runways to prevent Syrian aircraft from taking off, or disrupting communication between the regime leaders giving the orders and the commanders on the ground who would have to carry them out.
Obama has not asked the Pentagon to present specific military options, and there are no plans to put "boots on the ground" in Syria. But last year the Defense Department came up with a military analysis for the president, should he request it. It calculated that it could take up to 75,000 troops to secure Syria's chemical weapons facilities, if they were in danger of being looted. An actual deployment would likely involve far fewer ground troops, and from various nations, but it underscores the scope of the challenge. Any introduction of ground forces would have to be preceded by airstrikes to destroy Syria's air defenses, an operation which could take weeks or longer. The military assesses that Syria has about 50 production sites around the country, as well as some storage areas and research centers.