Congressional Democrats, signaling plans to become more assertive about Iraq, yesterday asked the director of national intelligence to brief senators on conditions there, including whether the conflict has strengthened Islamic terrorists rather than weakened them.

In a letter to director John D. Negroponte, top Democratic senators said they need more information on the anti-U.S. insurgency, allied support, training of Iraqi security forces and many other topics.

"Having the latest intelligence assessments from the National Intelligence Council (NIC) that take into account the coordinated and collective views of the Intelligence Community is critical to ensuring that U.S. policy is properly focused and resources correctly allocated to address the most pressing threats and challenges," the letter said. It was signed by Minority Leader Harry M. Reid (D-Nev.) and the ranking Democrats on committees dealing with intelligence, foreign relations and the military. It asks Negroponte to brief "all interested senators" behind closed doors, starting Oct. 5 and then about every 60 days thereafter.

The letter's more than 20 questions include "To what extent are Islamic extremists exploiting the Iraq conflict to recruit new, anti-U.S. jihadists to join or support their cause?" and "Have Al Qaeda and the global violent extremist movement gained strength or weakened as a result of the war in Iraq?"

It also asks about the intelligence community's "assessment of the strength, size, lethality and composition of the insurgency," and whether "fighters and techniques seasoned on the battlefield in Iraq are being exported to Western Europe, the United States, Afghanistan, or other regions?"

The letter comes as congressional Democrats say they plan to speak out more forcefully on Iraq in coming weeks. But the party faces significant divisions, with some members calling for a timetable for withdrawing U.S. troops, and others agreeing with President Bush that a timetable would help the insurgency.

At the Pentagon yesterday, Bush acknowledged that Americans are increasingly uneasy about the war's progress. "Listen, there are differences of opinion about the way forward," he said. "I understand that. Some Americans want us to withdraw our troops so that we can escape the violence. I recognize their good intentions, but their position is wrong. Withdrawing our troops would make the world more dangerous and make America less safe."

Bob Stevenson, spokesman for Senate Majority Leader Bill Frist (R-Tenn.), said the Democrats' letter "really is unnecessary" because Frist has initiated classified briefings on Iraq from Negroponte, Defense Secretary Donald H. Rumsfeld, Secretary of State Condoleezza Rice and others. "There is no need to have a partisan letter that is released . . . to generate press," he said.

At the Pentagon yesterday, President Bush reaffirmed the need to keep troops in Iraq.