Dubbed the "Powell Doctrine," Powell's code on the use of force has been ignored during the administration of President George W. Bush which opted for speed over mass in invading Iraq last year, leaving US forces embroiled in a protracted guerrilla war.

The 1990-1991 Gulf War, which Powell prosecuted as chairman of the Joint Chiefs of Staff under Bush's father, is a study in contrast with the approach to Iraq taken 12 years later under the leadership at the Pentagon of Defense Secretary Donald Rumsfeld.

Powell, an army general deeply influenced by his experience as a young soldier in Vietnam, deployed 500,000 US troops to Saudi Arabia for the limited objective of liberating Kuwait, which had been seized by Iraqi forces in August 1990.

President George H.W. Bush gained UN Security Council backing, won the approval of Congress, assembled a broad international coalition that included Arab countries, and sent coalition forces storming into Kuwait after intense aerial bombardment.

At Powell's recommendation, Bush halted the ground war after 100 hours, allowing Iraqi mechanized forces to escape, a decision that would later prove controversial.

US air and naval forces remained in the region for years afterwards, but most of the US ground force in Kuwait were quickly redeployed after the war.

Powell articulated his ideas on the use of force, which built on a doctrine on the use of force enunciated earlier by former Defense Secretary Caspar Weinberger, in post war speeches and an article in the winter 1992-93 edition of Foreign Affairs.

"We owe it to the men and women who go in harm's way to make sure that this is always the case and that their lives are not squandered for unclear purposes," he said in a 1992 speech.

"We must not, for example, send military forces into a crisis with an unclear mission they cannot accomplish -- such as we did when we sent the U.S. Marines into Lebanon in 1983," he said.

"We inserted those proud warriors into the middle of a five-faction civil war complete with terrorists, hostage-takers, and a dozen spies in every camp, and said, 'Gentlemen, be a buffer.' The results were 241 Marines and Navy personnel killed and a US withdrawal from the troubled area."

Powell, who remained as chairman of the Joint Chiefs of Staff into the first year of the Clinton administration, argued against US military involvement in the Balkans.

Though immensely influential, Powell's ideas were challenged by former secretary of state Madeleine Albright, who advocated the US military force to back up diplomacy.

As secretary of state, Powell was often at odds with a Pentagon leadership intent on using force unilaterally if necessary.