UNITED NATIONS -- In a recent speech, Hans Blix told his weapons inspectors exactly how to act in Iraq: Be driving and dynamic, but not angry and aggressive. Show some flexibility, but don't be pushed around.

He could have been describing himself.

The 74-year-old Swede is charged with telling the world whether Iraq has biological and chemical weapons and is complying with U.N. inspections. His report may not halt the United States' plans for war with Iraq, but it will likely make or break international support for it.

He comes to the job with years of experience, but mixed reviews. "Extremely prudent, careful and courageous," says former U.S. diplomat Richard Gardner, an old friend. "Totally incompetent," says Per Ahlmark, Sweden's former deputy prime minister.

But for the U.N. Security Council, Blix was the right person at a difficult time.

Compromise candidate

In January 2000, he became the compromise candidate for chief U.N. weapons inspector after Washington's pick -- another Swede -- was rejected by a badly divided council.

At the time, inspectors had been out of Iraq for more than a year and there was no sign they would be allowed to go back. Still, Blix, an international law expert who previously ran the U.N. nuclear watch dog agency, set out to reshape the inspections regime, whose reputation had been tainted by abrasive tactics and allegations that inspectors spied for the United States and Israel.

His first move was to hire Demetrius Perricos, a nervy Greek nuclear expert who had been his deputy at the International Atomic Energy Agency in Vienna. Together, they turned to alternative intelligence sources, such as commercially available satellite photos, rather than relying heavily on Washington's data.

Blix's office, the U.N. Monitoring, Verification and Inspection Commission or UNMOVIC, followed its orders to the letter, hiring a new international crew of technical experts and inspectors. Meanwhile, Blix built a close relationship with Secretary-General Kofi Annan and made clear his allegiances were strictly to the Security Council, which oversees his mission.

The diplomatic maneuvering won him accolades for maintaining a tough, neutral, yet businesslike approach to the job while he waited patiently for a way back to Baghdad.

The opportunity came this September when Iraq, under enormous international pressure generated by President Bush's tough challenge to the U.N. General Assembly, agreed to the unconditional return of inspectors.

Now Blix is armed with a new Security Council resolution that broadens his powers. He's reluctant to overdramatize his role, rejecting the notion that "we hold war and peace in our hands," but clearly his report card on Iraqi compliance will be the deciding factor for many U.S. allies unsure about another conflict with Iraq.

"The burden will be on Hans and what kind of a report he'll present to the council," said Gardner, a former ambassador who teaches international law at Columbia University -- where he and Blix met 40 years ago.

Gardner is confident in Blix, saying, "Anyone who thinks he can be pushed around is wrong."

Not everyone agrees.

"He's not strong enough to be the head inspector in a tyranny of Saddam Hussein," said Ahlmark, who entered Swedish politics with Blix years ago. "It's much too important a job for him and he's too easily deceived."

Blix will be tested from the outset by what kind of sites he chooses to inspect, how aggressively he pursues his orders, and whether he can solve a decade-old mystery about Iraq's weapons programs.

Nuclear inspections will be handled by the new chief of the IAEA, although Blix has plenty of expertise in that area from his time with the agency.

Former colleagues say Blix's IAEA was tough on North Korea but not on Iraq. "They were asleep," said David Albright, an American who worked on the nuclear inspections team in Iraq.

Blix once publicly accused an inspector of being too tough on Iraq, leading some to charge that he trusted the Iraqis more than his own inspectors.

For the new chemical and biological inspections to work, Albright said, the Security Council would have to continually pressure Blix "to do a thorough and tough job. He has to be held accountable for what he does."

Blix's 1991-97 tenure at the IAEA covered all but the last year of nuclear inspections in Iraq. He left the day-to-day aspects of inspections to his deputies and only stepped in to the larger political battles.

His relationship with Rolf Ekeus, another Swede who ran the U.N. side of weapons inspections during the mid-1990s, was so bad "you could hear them screaming at one another over the phone," Albright said.

"The rivalry affected the inspections."

Today Blix could easily be spending retirement at home with his wife in Sweden, building on his collection of oriental rugs. But that's part of what made him an attractive candidate for the Iraq job.

"He has no further ambition," says Singapore's U.N. ambassador Kishore Mahbubani.

Annan, who nominated Blix for the job, says he is "a very experienced man with keen judgment. I expect him to do very well."

Blix is also liked simply for being so different from his Australian predecessor, Richard Butler, who was outspoken and charming but sometimes undiplomatic, angering council members who felt he was antagonizing Iraq and siding with Washington.

Eventually, Butler's inspections regime fell apart. Without consulting the Security Council, he ordered inspectors to leave Iraq in December 1998 ahead of U.S. and British airstrikes and was discredited by charges that some of his inspectors were spying.

"Blix has shown he's going to be honest and impartial and that he's going to serve the United Nations and not just one of its members. He says he'll avoid the mistakes of Butler," said Fayssal Mekdad, deputy ambassador of Syria, a Security Council member.

Iraqi Ambassador Mohammed Al-Douri seems willing to give the new man the benefit of the doubt, noting: "Blix says he'll be fair."