* Some lawmakers using conflict to try to ease Pentagon cuts
* Costs could escalate if military action lasts longer
* Strike on Syria could buoy weapons-makers' shares
By Andrea Shalal-Esa and David Alexander
WASHINGTON, Sept 2 (Reuters) - The U.S. military's decision to move an aircraft carrier into the Red Sea to help out with any "contingencies" underscores concerns a strike on Syria could evolve into another costly war as U.S. defense spending faces massive, mandatory cuts.
Current and former military officials say the cost of firing cruise missiles at selected targets in Syria would be relatively easily absorbed, and analysts say the effect on U.S. weapons makers would be relatively minimal.
But some U.S. lawmakers worry a strike against Syria could trigger a broader conflict.
They are using that argument as another reason to avert more than $500 billion in military spending cuts facing the Pentagon over the next decade under the process known as "sequestration," on top of $487 billion in cuts that were already planned.
"We cannot keep asking the military to perform mission after mission with sequestration and military cuts hanging over their heads," Republican Buck McKeon, chairman of the House of Representatives Armed Services Committee, told CNN on Monday.
Top military leaders have repeatedly warned lawmakers that further cuts will jeopardize the U.S. military's readiness to respond to crises like the one now playing out over Syria's suspected use of chemical weapons against its own citizens.
President Barack Obama's administration says the Syrian government must be punished for the Aug. 21 chemical weapons onslaught in the Damascus suburbs that killed over 1,400 people.
But Obama halted plans for a strike against President Bashar al-Assad's forces until he receives congressional approval.
Loren Thompson, chief operating officer of the Lexington Institute consultants' group, said the administration's proposed limited strike on Syria could buoy shares in major weapons makers such as missile maker Raytheon Co and Lockheed Martin, which builds the Aegis combat system used on Navy ships.
Weapons makers are looking to foreign military sales and commercial markets to offset the downturn in U.S. military spending, but a new overseas conflict could increase demand for expendable items such as Raytheon's Tomahawk missiles.
"Any chance of military action tends to boost defense shares and bolster the case for defense spending," Thompson said, noting there was always the potential for escalation, despite the relatively small cost of cruise missile strikes.
Obama has said he will not put U.S. soldiers on the ground in Syria, but military planners say they are preparing for all possible "contingencies," a fact reflected by the decision to reroute the USS Nimitz carrier strike group to the Red Sea, instead of letting it return home.
"The prospect of military action has to raise questions about whether sequestration should continue," Thompson said.
A limited strike using Tomahawk missiles against Syrian command structures and chemical weapons delivery systems would not be an expensive mission by Pentagon standards.
Tomahawk missiles cost an average of about $1.2 million each, so the overall price for a limited operation using missiles would depend on how many targets the administration decided to hit and the number of missiles it would have to use.
Retired Navy Admiral Gary Roughead, who served as chief of naval operations during the allied strike on Libya in March 2011, said the cost of a limited strike on Syria was unlikely to require a supplemental budget submission, unless the Obama administration decided to launch a more protracted campaign.
"We did Libya and pretty much absorbed that out of the budget, he said."
But the cost for strikes against Syria could rapidly escalate if the response prompted additional U.S. action, such as trying to destroy Assad's air defenses or establishing a no-fly zone with aerial patrols.
The military says it will be prepared no matter what, but analysts said the budget cuts were affecting how the Pentagon was approaching the situation with Syria.
"You know ... what the impact has been on Air Force readiness. That's real. It does seriously limit the ability to quickly escalate. It does limit proficiency. You can't recover it without significant time," said Anthony Cordesman, a defense analyst at the Center for Strategic and International Studies.