The U.S. has established an operational plan to deploy 20 marine brigades to the Korean Peninsula in case of a North Korean invasion into the South, U.S. House Armed Services Chairman Howard McKeon said Tuesday.

During a forum in Washington, McKeon said that U.S. Marine Corps Commandant Gen. James Amos told him that most of the U.S. marines are to be dispatched to defend South Korea under the plan, according to Yonhap.

The Republican lawmaker said that with the congressionally mandated budget cuts, or sequestration, the number of U.S. marines is to be reduced to 175,000 to form only 21 brigades, noting that only one brigade may remain in the U.S. while the rest are to be sent to the peninsula in case of a war.

McKeon’s claim was apparently welcomed news in South Korea, where some were concerned that with the U.S. troop drawdown, Washington would be reluctant to commit a large number of ground troops for peninsular contingencies.

Under the allies’ joint war plan, the U.S. is to send its 690,000 troops to the peninsula in case of an all-out war. But given Washington’s plan to slash its ground troops, analysts said that the plan was no longer realistic.

Earlier this year, the Pentagon said that due to budget cuts, the active-duty army will be reduced over the next five years to between 440,000 and 450,000 from the current 520,000.

Washington officials argued that the force reduction is to “normalize” its troop structure after more than a decade of war in Iraq and Afghanistan. But some observers stressed the need to craft a more viable plan to prepare for peninsular contingencies.

Bruce Bennett, a senior defense analyst at the RAND Corporation, said that the U.S. Army cuts will not seriously reduce U.S. deployments to South Korea if conflict occurs here.

Bennett put the baseline number of the U.S. Army troops at 480,000, dismissing the current figure of 520,000. He said that the original figure rose as wars in Iraq and Afghanistan progressed.

“Still, 480,000 is the rough baseline from which (Defense) Secretary Hagel is reducing the Army to about 440,000 or 450,000 ― more like a 6 to 8 percent manpower decrease,” he said. “A 6 to 8 percent personnel decrease in the U.S. Army will not prevent substantial U.S. Army deployments to Korea.”

By Song Sang-ho (sshluck@heraldcorp.com)