The Bush administration, escalating a diplomatic campaign to convince Iraq that it must fully disarm or face a U.S.-led invasion, is dispatching high-level Pentagon and State Department officials for consultations in coming weeks with key allies around the world.

Deputy Defense Secretary Paul D. Wolfowitz will be the first to depart, heading out over the weekend for meetings with NATO allies in Brussels and British officials in London on Monday before beginning critical talks with Turkey's new government Tuesday in Ankara.

He will be followed by Deputy Secretary of State Richard L. Armitage, Deputy National Security Adviser Stephen Hadley and other officials on trips that have been planned on the assumption that Iraqi President Saddam Hussein will comply with the U.N. weapons inspections process only if he believes it has strong international backing.

"You have to apply pressure to keep Saddam Hussein focused," said one senior State Department official. "The best way to avoid a war is to prepare for all contingencies."

The meetings will include sessions with both strong U.S. military allies, such as Australia, and key political allies, such as Japan.

Another senior administration official mentioned China as a possible interlocutor, saying support from China would go a long way toward convincing Hussein that the U.N. Security Council would not tolerate efforts by Iraq to impede the work of the weapons inspectors, which began yesterday with visits to an engineering center and a military-industrial plant outside Baghdad.

The administration's new diplomatic offensive comes on top of efforts already underway to build a coalition for possible military action against Iraq if the inspections process breaks down. The State Department has contacted 51 nations on behalf of U.S. Central Command, which would oversee any war against Iraq, asking for specific contributions such as combat forces or overflight rights for U.S. warplanes.

As part of that effort, the State Department has asked several countries whether they would host U.S. programs to train Iraqi opposition forces. An agreement to have Hungary provide the first such base for that training appears near to being reached, other administration sources said.

The administration wants to build as broad a military coalition as possible, both for symbolic and military reasons, the senior administration official said. Although only Britain and a handful of other countries have been asked to contribute combat troops and special forces, the official said, the war in Afghanistan has demonstrated that even small contributions -- such as Norway's deployment of special forces trained in cold weather mountain fighting -- can be extremely important.

The administration's timetable for possible military action, the official said, is to some extent driven by the U.N. inspections process, at least in the near term. Military action could not come before Dec. 8, when Iraq must submit a detailed inventory of its weapons of mass destruction and its missile systems for delivering them, the official said.

Once that inventory is submitted, the official said, time would be necessary to allow inspectors to attempt to verify the validity of Iraq's declaration. But the official made it clear that the United States is in a position to use military force immediately if Iraq takes provocative action against its neighbors.

Wolfowitz's talks in Ankara on Tuesday will be the first high-level meeting between a senior Pentagon official and officials from the newly elected Turkish government led by the Justice and Development Party, which has Islamic roots.

The administration wants a deal in which Turkey would contribute military forces and allow U.S. forces to use Turkish bases to launch an invasion of northern Iraq. Wolfowitz, at the least, wants to come away with a sense of how long it will take to get an answer from the new government, the administration official said.

Although Pentagon officials believe they have enough support and basing rights in the region to topple Hussein's government without Turkey's help, the official said, Wolfowitz will try to sell Turkey on the notion that its full military assistance would make any invasion of Iraq much shorter and much less damaging to the region.

Turkish military cooperation, the official said, would be a critical part of presenting Hussein with as robust a military invasion force from the north as possible.

To persuade the Turks to join the fight, the official said, Wolfowitz will offer them an aid package and a guarantee that the United States shares Turkey's opposition to an independent Kurdish state in northern Iraq.

On the issue of training the Iraqi opposition, Defense Secretary Donald H. Rumsfeld is expected to consider and approve a plan next week, administration sources said. The Hungarian government, which confirmed receiving a request to host the training, has not yet agreed but is expected to do so when asked for its final approval, the sources added.

The Iraqis would serve as interpreters and escorts for U.S. ground forces invading Iraq if such an attack occurs, the sources said. But even before then, the training would have the diplomatic effect of underscoring to Hussein that European nations are lending support to the U.S. campaign against him.

The Army has assembled a group of trainers at Fort Jackson, S.C., a Pentagon official said. The commander of the training program will be Army Maj. Gen. David W. Barno, who currently commands Fort Jackson, an official said.