Top American officials in Seoul are discussing sensitive plans for sweeping cuts in U.S. troop numbers in South Korea.

A U.S. delegation led by Assistant Secretary of Defense Richard Lawless met with South Korean officials and reportedly proposed withdrawing up to one-third of the 37,000 U.S. troops in South Korea.

The United States has maintained a military presence in South Korea since the Korean War ended in 1953, chiefly as a deterrent against a North Korean attack.

Speaking to reporters before the talks, South Korea's National Security Advisor Kwon Chin-Ho says troop realignment must not undermine deterrence. The United States announced plans in May to shift 3,600 troops from South Korea to Iraq, the first time the United States has reduced its armed forces in South Korea since the end of the Cold War.

The two-day talks will also cover plans to move about 7,000 U.S. troops from their base near the heavily armed border with North Korea to a new military camp well south of Seoul.

In a speech to the Korean parliament, South Korea's President Roh Moo-hyun said he values the alliance, but wants to reduce his country's dependence on Washington.

Nevertheless, the U.S. proposal has left many in South Korea worried that the troop withdrawal may make the country more vulnerable to an attack from the North.

North Korea has the world's biggest army for the size of its population, and its more than one million troops dwarf the size of the combined South Korean - U.S. forces.

South Korean officials say the U.S. plans to pull its troops out by the end of next year, but South Korea favors a more gradual withdrawal, delaying the final cuts for seven years.

Despite discussions on troop reduction, the United States has been careful to re-affirm its commitment to South Korea's defense.

Washington recently announced plans to invest $11 billion to upgrade U.S. military capabilities in Asia.

The upgrades and troop realignment occur against the backdrop of the standoff with North Korea over its nuclear weapons programs.