South Korea's interim head of state, Goh Kun, has pledged to continue his country's alliance with the United States as the cornerstone of Seoul's foreign policy. Mr. Goh spoke a day after the National Assembly staged South Korea's first impeachment of a sitting president, Roh Moo-hyun.

Mr. Goh, the country's prime minister, will run the country until the Constitutional Court rules on whether to uphold Friday's impeachment vote -a process that could take up to six months.

He used a television appearance Saturday to vow to keep South Korea's political and economic policies on an even keel. He said he would continue with government plans to deploy peacekeeping troops to help rebuild Iraq, to maintain the alliance with the United States, and to seek a peaceful end to the North Korean nuclear crisis.

Mr. Goh, who also assumed leadership of the South Korean armed forces, ordered the 700,000-strong military to heighten its security posture along the heavily-fortified border with North Korea. The Defense Ministry said it saw no signs of unusual North Korean troop movements.

Mr. Goh, 66, who has served in six successive governments, has earned the nicknames "Mr. Stability" and "Master Administrator" for his ability to survive the turbulent South Korean political landscape.

Friday's impeachment vote stripped President Roh Moo-hyun of his presidential powers on an interim basis, for violations of election law, 13 months into his five-year term.

In order for Mr. Roh to be permanently removed from office, the nine-member Constitutional Court must uphold the impeachment. Mr. Roh predicted after Friday's vote that he would ultimately be returned to office.

South Korean Foreign Minister Ban Ki-moon telephoned Secretary of State Colin Powell late Friday to offer reassurances on foreign policy.

The Seoul stock market dropped five percent Friday before rallying slightly at the close. Later, thousands of South Koreans held candlelight vigils to protest the impeachment, while opinion polls indicate more than seven out of 10 citizens said they believe the suspension of Mr. Roh's duties was wrong.

The two main opposition parties, the conservative Grand National Party and the Millennium Democratic Party, joined forces to impeach Mr. Roh.

They said they moved after the president refused to apologize for illegally trying to influence the outcome of next month's parliamentary election. The parties also charged him with corruption and incompetence.

South Korea's election commission reprimanded Mr. Roh last week for trying to swing the vote in favor of his Uri Party, a violation of the rules. But the commission took no further action, judging the violation to be minor.