Washington ? The Pentagon’s intelligence agency had no hard evidence of Iraqi chemical weapons last fall but believed Iraq had a program in place to produce them, the agency’s chief said Friday.

The assessment suggests a higher degree of uncertainty about the immediacy of an Iraqi threat — at least with regard to one portion of its banned weapons programs — than the Bush administration indicated publicly in building its case for disarming Iraq, with force if necessary.

Two months after the major fighting in Iraq ended, the United States has yet to find any chemical, biological or nuclear weapons, although it did find two trailers it judged to be mobile laboratories for producing bioweapons.

The absence so far of a “smoking gun” has raised questions about the quality of U.S. intelligence before the war and whether the administration exaggerated the urgency of an Iraqi threat.

Vice Adm. Lowell Jacoby, director of the Defense Intelligence Agency, discussed the matter at a Capitol Hill news conference Friday as the administration scrambled to respond to news reports about excerpts from a September 2002 DIA report on facilities and other pieces of Iraq’s arms-building infrastructure.

Jacoby said his agency concurred in an intelligence community consensus last fall that Iraq had a program for weapons of mass destruction. But the DIA was unable to pinpoint any locations.

“We could not specifically pin down individual facilities operating as part of the weapons of mass destruction program, specifically the chemical warfare portion,” Jacoby said at a joint news conference with Sen. John Warner, R-Va., and Stephen Cambone, the Pentagon’s intelligence chief.

They spoke after the Senate Armed Services Committee met privately with Jacoby, Cambone and an unidentified CIA representative to discuss prewar intelligence on Iraq’s weapons programs.

At the White House, visiting Portuguese Prime Minister Jose Durao Barroso told reporters that President Bush told him Friday he has “full confidence in the intelligence reports he received about the possession of weapons of mass destruction by the former Iraqi authorities.”

The administration began building its case against Iraq last August in a series of speeches by Vice President Dick Cheney. “There is no doubt that Saddam Hussein now has weapons of mass destruction,” Cheney told a Veterans of Foreign Wars convention on Aug. 26. “There is no doubt he is amassing them to use against our friends, against our allies and against us.”

In September Defense Secretary Donald H. Rumsfeld joined in.

“We do know that the Iraqi regime has chemical and biological weapons,” Rumsfeld told the House Armed Services Committee on Sept. 18. “His regime has amassed large, clandestine stockpiles of chemical weapons — including VX, sarin, cyclosarin and mustard gas.”

In his description of the still-classified DIA report, Jacoby drew a distinction between the level of certainty about Iraq’s pursuit of weapons and the existence of actual chemical weapons.

“As of 2002, in September, we could not reliably pin down — for somebody who was doing contingency planning — specific facilities, locations or production that was under way at a specific location at that point in time,” he said.

The report “is not in any way intended to portray the fact that we had any doubts that such a program existed,” he said.

Rumsfeld recently raised the possibility that Iraq destroyed such weapons before the war started March 20. He also has said he believes some remain and will be discovered when U.S. search teams find knowledgeable Iraqis who are willing to disclose the locations.

In making its case for invading Iraq, the administration also argued that Iraq was seeking to develop nuclear weapons and that it might provide mass-killing weapons to terrorists.

On Friday, a small team of United Nations nuclear experts arrived in Baghdad to begin a damage assessment at Iraq’s largest nuclear facility, known as Tuwaitha. It was left unguarded by American and allied troops during the early days of the war and was pillaged by villagers.

The arrival of the team — whose members are not weapons inspectors — marked the first time since the Iraq war began that representatives from the U.N.’s International Atomic Energy Agency returned to the country. The agency had long monitored Iraq’s nuclear program.

The DIA’s analysis is just one piece of an intelligence mosaic that Rumsfeld and other senior administration officials could consider in making their own assessment of Iraq’s chemical and biological weapons capability. Congress is reviewing the prewar intelligence to determine whether the administration overplayed the weapons threat in order to justify toppling the Iraqi government.