In a letter to Congress, Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff, has laid out in unclassified fashion the U.S. military's options for Syria that have been presented to the White House for consideration.

He also cautioned about unintended consequences of U.S. military action.

"Once we take action, we should be prepared for what comes next," he said. "Deeper involvement is hard to avoid."

The options and Dempsey's concerns for U.S. military options in Syria are contained in a letter he sent Friday to Sen. Carl Levin, D-Mich., who had requested an unclassified assessment of potential options for Syria.

During Thursday's confirmation hearing before the Senate Armed Services Committee, Dempsey and Sen. John McCain, R-Ariz, had a tense exchange, during which McCain said Dempsey had not provided the committee with adequate information about U.S. military options in Syria. At the hearing, Committee Chairman Levin asked Dempsey to provide an assessment about U.S. military options.

Following the hearing, McCain told reporters that he would place a hold on Dempsey's nomination to serve another two-year term as the nation's top military officer unless he received more information from Dempsey.

In his July 19 letter, Dempsey listed the five U.S. military options as : Train, Advise and Assist the Opposition; Conduct Limited Stand-off Strikes; Establish a No-Fly Zone; Establish Buffer Zones; Control Chemical Weapons.

He pointed out that the use of the options would be a political decision that should not be carried out lightly and would be "no less than an act of war."

As Syria's civil war has raged for two years, the Obama administration has called on Syrian President Basher al Assad to step aside to make way for a political transition. U.S. military options have always been seen as limited and have taken a back-burner to the administration's pursuit of a diplomatic track and growing support for Syrian opposition forces. Just last month, the administration announced it would provide some Syrian rebels with lethal aid that would include small arms and ammunition.

Dempsey repeated a point he has made in the past - that the unintended consequences on the region should be weighed if military force is to be used.

"We should also act in accordance with the law, and to the extent possible, in concert with our allies and partners to share the burden and solidify the outcome," said Dempsey.

According to Dempsey, establishing a no-fly zone over Syria would require "hundreds of ground and sea-based aircraft, intelligence and electronic warfare support, and enablers for refueling and communications. Estimated costs are $500 million initially, averaging as much as a billion dollars per month over the course of a year. "

The risks, he added, are that American jets could be downed and, "it may also fail to reduce the violence or shift the momentum because the regime relies overwhelmingly on surface fires - mortars, artillery, and missiles.

Controlling Syria's large chemical weapons stockpile, he said, would require the use of lethal force to secure the sites, which can be done by "destroying portions of Syria's massive stockpile, interdicting its movement and delivery, or by seizing and securing program components. "

Thousands of special operations forces and other ground forces would be needed to assault and secure critical sites, and a no-fly zone would also be required. Costs could average well over $1 billion per month.

"The impact would be the control of some, but not all chemical weapons," said Dempsey. "It would also help prevent their further proliferation into the hands of extremist groups. Our inability to fully control Syria's storage and delivery systems could allow extremists to gain better access. Risks are similar to the no-fly zone with the added risk of U.S. boots on the ground."

The f ull text of the letter is below:

THE JOINT CHIEFS OF STAFF

The Honorable Carl Levin

Chairman

Committee on Armed Services

United States Senate

Washington, DC 20510

Dear Mr. Chairman:

On 18 July 2013 , you asked me to provide an unclassified assessment of options for the potential use of U.S. military force in the Syrian conflict. It offers my independent judgment with as much openness as this classification allows. I am mindful that deliberations are ongoing within our government over the further role of the United States in this complex sectarian war. The decision over whether to introduce military force is a political one that our Nation entrusts to its civilian leaders. I also understand that you deserve my best military advice on how military force could be used in order to decide whether it should be used.

At this time, the military's role is limited to helping deliver humanitarian assistance, providing security assistance to Syria's neighbors, and providing nonlethal assistance to the opposition. Patriot batteries are deployed to Turkey and Jordan for their defense against missile attack. An operational headquarters and additional capabilities, including F-16s, are positioned to defend Jordan. We are also prepared for the options described below:

Train, Advise, and Assist the Opposition. This option uses nonlethal forces to train and advise the opposition on tasks ranging from weapons employment to tactical planning. We could also offer assistance in the form of intelligence and logistics. The scale could range from several hundred to several thousand troops with the costs varying accordingly, but estimated at $500 million per year initially. The option requires safe areas outside Syria as well as support from our regional partners. Over time, the impact would be the improvement in opposition capabilities. Risks include extremists gaining access to additional capabilities, retaliatory crossborder attacks, and insider attacks or inadvertent association with war crimes due to vetting difficulties.

Conduct Limited Stand-off Strikes. This option uses lethal force to strike targets that enable the regime to conduct military operations, proliferate advanced weapons, and defend itself. Potential targets include high-value regime air defense, air, ground, missile, and naval forces as well as the supporting military facilities and command nodes. Stand-off air and missile systems could be used to strike hundreds of targets at a tempo of our choosing. Force requirements would include hundreds of aircraft, ships, submarines, and other enablers. Depending on duration, the costs would be in the billions. Over time, the impact would be the significant degradation of regime capabilities and an increase in regime desertions. There is a risk that the regime could withstand limited strikes by dispersing its assets. Retaliatory attacks are also possible, and there is a probability for collateral damage impacting civilians and foreigners inside the country.

Establish a No-Fly Zone. This option uses lethal force to prevent the regime from using its military aircraft to bomb and resupply. It would extend air superiority over Syria by neutralizing the regime's advanced, defense integrated air defense system. It would also shoot down adversary aircraft and strike airfields, aircraft on the ground, and supporting infrastructure. We would require hundreds of ground and sea-based aircraft, intelligence and electronic warfare support, and enablers for refueling and communications. Estimated costs are $500 million initially, averaging as much as a billion dollars per month over the course of a year. Impacts would likely include the near total elimination of the regime's ability to bomb opposition strongholds and sustain its forces by air. Risks include the loss of U.S. aircraft, which would require us to insert personnel recovery forces. It may also fail to reduce the violence or shift the momentum because the regime relies overwhelmingly on surface fires-mortars, artillery, and missiles.

Establish Buffer Zones. This option uses lethal and nonlethal force to protect specific geographic areas, most likely across the borders with Turkey or Jordan. The opposition could use these zones to organize and train. They could also serve as safe areas for the distribution of humanitarian assistance. Lethal force would be required to defend the zones against air, missile, and ground attacks. This would necessitate the establishment of a limited no-fly zone, with its associated resource requirements. Thousands of U.S. ground forces would be needed, even if positioned outside Syria, to support those physically defending the zones. A limited no-fly zone coupled with U.S. ground forces would push the costs over one billion dollars per month. Over time, the impact would be an improvement in opposition capabilities. Human suffering could also be reduced, and some pressure could be lifted off Jordan and Turkey. Risks are similar to the no-fly zone with the added problem of regime surface fires into the zones, killing more refugees due to their concentration. The zones could also become operational bases for extremists.

Control Chemical Weapons. This option uses lethal force to prevent the use or proliferation of chemical weapons. We do this by destroying portions of Syria's massive stockpile, interdicting its movement and delivery, or by seizing and securing program components. At a minimum, this option would call for a no-fly zone as well as air and missile strikes involving hundreds of aircraft, ships, submarines, and other enablers. Thousands of special operations forces and other ground forces would be needed to assault and secure critical sites. Costs could also average well over one billion dollars per month. The impact would be the

control of some, but not all chemical weapons. It would also help prevent their further proliferation into the hands of extremist groups. Our inability to fully control Syria's storage and delivery systems could allow extremists to gain better access. Risks are similar to the no-fly zone with the added risk of U.S. boots on the ground.

Too often, these options are considered in isolation. It would be better if they were assessed and discussed in the context of an overall whole-of-government strategy for achieving our policy objectives in coordination with our allies and partners. To this end, I have supported a regional approach that would isolate the conflict to prevent regional destabilization and weapons proliferation. At the same time, we should help develop a moderate opposition-including their

military capabilities-while maintaining pressure on the Assad regime.

All of these options would likely further the narrow military objective of helping the opposition and placing more pressure on the regime. We have learned from the past 10 years; however, that it is not enough to simply alter the balance of military power without careful consideration of what is necessary in order to preserve a functioning state. We must anticipate and be prepared for the unintended consequences of our action. Should the regime's institutions collapse in the absence of a viable opposition, we could inadvertently empower extremists or unleash the very chemical weapons we seek to control.

I know that the decision to use force is not one that any of us takes lightly. It is no less than an act of war. As we weigh our options, we should be able to conclude with some confidence that the use of force will move us toward the intended outcome. We must also understand risk-not just to our forces, but to our other global responsibilities. This is especially critical as we lose readiness due to budget cuts and fiscal uncertainty. Some options may not be feasible in time or cost without compromising our security elsewhere. Once we take action, we should be prepared for what comes next. Deeper involvement is hard to avoid. We should also act in accordance with the law, and to the extent possible, in concert with our allies and partners to share the burden and solidify the outcome.

Thank you for this opportunity to share my assessment. The classified versions of all the options described here have been presented to the National Security Staff for consideration by the Principals and the President. They have also been presented to the Congress in several briefs, including one recently provided by the Vice Chairman of the Joint Chiefs of Staff.

Sincerely,

Martin E. Dempsey

General, U.S. Army