The United States is nudging toward expanding its stated war aims to add the toppling of Saddam Hussein and partial occupation of Iraq. Surging beyond original aims proved disastrous in Korea and Vietnam.

When communist North Korea invaded South Korea in June 1950, President Harry Truman rallied the United Nations to "repel the aggressors."But once North Korean troops were chased back across the border, Truman couldn't pass up the chance to crush Kim Il Sung's regime and achieve the non-communist reunification of Korea.

As U.S. troops moved north, China warned it could not accept an American army on its border. Gen. Douglas MacArthur assured Truman that China wouldn't enter the war. It did, massively.

The U.N. command stopped the Chinese offensive south of the South Korean capital, Seoul, and the war bogged down into a bloody battle of attrition for two more years before the 1953 armistice.

By then, the number of Americans killed in action soared to 54,246, and 1.3 million South Koreans, 900,000 Chinese and 520,000 North Koreans died. Korea is still divided. Kim Il Sung is still in power.

In Vietnam, after France failed to quash Ho Chi Minh's communist guerrillas, President Dwight Eisenhower in 1954 pledged to support the remnant South Vietnamese government to maintain "a strong, viable state capable of resisting attempted subversion or aggression through military means."

Ten years later, President Lyndon Johnson wrung from Congress the Tonkin Gulf resolution authorizing him to "repel any ground attack" on U.S. forces and "prevent further aggression."

The war ended 11 years later after 58,021 Americans, 254,000 South Vietnamese and an estimated 1 million North Vietnamese died. South Vietnam fell to North Vietnam, and Ho Chi Minh and some of his top comrades have died of old age.

In the case of Iraq, there's only a slim chance that Mikhail Gorbachev's peace formula will persuade Saddam Hussein to leave Kuwait and end the war.

With U.S. and allied armies in the gulf ready to launch a ground assault on Iraqi troops before wind storms and hot weather hamper operations, the bloody climax of the war looms ahead this week.

The stated U.S. - and U.N. - aims are to achieve Iraq's "unconditional withdrawal from Kuwait," cancellation of its annexation of Kuwait and restoration of the ousted emir's government. Since the war began Jan. 16, the Bush administration has expanded the original aims:

- The air war has not only damaged Iraq's capacity to maintain and reinforce its 500,000-plus troops in Kuwait but also crippled Iraq's strategic military capability for years to come.

- Because a frontal allied assault on heavy Iraqi defensive positions in Kuwait would be foolish, the offensive will likely knife into Iraqi territory to the west and perhaps north of Kuwait, to surround and kill Iraqi troops.

At that point, Bush will have to decide: Leave well enough alone, occupying Kuwait and southern Iraq until a substitute force takes over, or, following "the logic of war," push north to demolish Iraq's strategic reserve or even press on to Baghdad.

The consequences of pursuit would be not only higher casualties but the disastrous impact on the Arab world of pictures of U.S. troops planting the American flag in an Arab capital.

To put it mildly, that would surely exceed the original war aims.

(Walter Friedenberg is foreign affairs correspondent of Scripps Howard News Service.)