It was an unconventional move in an unconventional war when Defense Secretary Donald H. Rumsfeld, nearly three years ago, assigned responsibility for the military's counterterrorism effort to the U.S. Special Operations Command and provided more troops, helicopters, gunships and other equipment to carry out the new mission.

The command's highly skilled forces, experts in stealth and agility, had just proved their worth by rallying Afghan militia to oust al Qaeda fighters and the Taliban government. Although not accustomed to running military campaigns, the special operators appeared particularly well-suited to take the lead in the worldwide battle against shadowy terrorists.

But the expanded effort has not developed as quickly or efficiently as hoped, handicapped in part by the continuing demands of conflicts in Iraq and Afghanistan, and also by a lack of experience at command headquarters in developing long-range strategic plans and coordinating with other government organizations, say defense officials, military officers and outside analysts.

Rumsfeld himself expressed frustration last month during a briefing by Vice Adm. Eric Olson, the deputy chief of Special Operations Command. According to several people at the closed-door Oct. 5 session, Rumsfeld responded testily when told of significant deficiencies in the command, pressing Olson on what had become of all the resources that had been poured into it.

"He said something like, 'What have you guys been doing for the past few years?' " recounted one person who was in the room with other top civilian officials and military officers. "He was hearing stuff about shortfalls here and there, and he was pretty upset."

Other participants placed at least some of the blame for the tense exchange on poorly devised briefing slides, which were intended to make the point that without more investment, the command, known as Socom, could face diminishing capabilities. In any case, asked about the meeting, Lawrence T. Di Rita, the Pentagon's chief spokesman, said that it made clear Rumsfeld's "real sense of urgency" for Socom to take "creative and aggressive" action.

Six days after the session, Rumsfeld traveled to Socom headquarters at MacDill Air Force Base in Florida for a more detailed briefing about the command's capabilities and future plans from Army Gen. Bryan D. Brown, its chief. But the Pentagon leader still wanted an outside assessment, which he ordered from a three-man team headed by Wayne A. Downing, a retired four-star general who led Socom from 1993 to 1996.

The team was given three weeks -- not enough time for an exhaustive study but long enough for a concise report on steps to help Socom perform more effectively. Its classified recommendations were submitted to Rumsfeld on Nov. 9.

Socom's growing role is a central focus of a larger Pentagon review of missions and weapons now underway. The review is widely expected to emphasize the need for more flexible U.S. forces to deal not only with conventional conflicts but also with untidy insurgencies, terrorist networks and homeland defense needs -- all areas in which Special Operations troops have important parts to play.

Defending his command's performance, Brown said at a luncheon meeting of reporters yesterday that "we have moved incredibly fast in a lot of new areas." He stressed the novelty of Socom's transformation into a "global warfighting command," after having been designed in 1987 to play a supporting role training and equipping the military's most highly skilled forces.

He quoted Rumsfeld as saying at the end of last month's Florida visit, "You are making tremendous progress." Although declining to provide specifics about the Downing review, he said it echoes other recent studies that have concluded Socom is "on the right track."

Since the Sept. 11, 2001, terrorist attacks, the command's budget has grown $2.4 billion, to more than $8 billion a year, and its forces have increased by 5,700 troops, up to about 54,000. But despite the growth, Socom's forces are stretched thin.

According to Pentagon figures, al Qaeda cells operate in about 60 countries, and Islamic insurgencies exist in nearly 20. Yet of 7,000 Special Operations troops deployed outside the United States, about 88 percent operate in the Central Command's region, which includes Iraq and Afghanistan, leading the hunt for high-level insurgents and providing special counterterrorism training to national forces.

"Essentially what we have is a two-country solution to a 60-country problem," Michael Vickers, a defense analyst and former Army Special Forces officer who served on Downing's review team, told a House subcommittee last month.

He cited two main "capability shortfalls" in Socom -- an immediate one involving its ability to locate and track terrorists, and an "emerging" one relating to Socom's ability to conduct secret air operations over countries with increasingly advanced air defenses. Vickers estimated that Socom's forces, both for combat missions and foreign military training efforts, need to increase by as much as 40 percent.

Although there appears little argument about Socom's need for more troops, the command has come under criticism for less-than-optimum use of its existing ranks, which range from Army Special Forces teams skilled in foreign military training to Delta Force and Navy SEAL units honed for clandestine operations.

"You have some of our real elite units doing some lesser-type missions, and then you have some units that should be doing more training doing direct-action," said a military officer at the Pentagon who has reviewed Socom's performance and requirements. "So it's a real issue of focus."

Other analysts say Socom is still struggling to develop the long-range strategic plans for guiding the war on terrorism.

"We need to develop a skill base within the Special Operations community that's not just action-oriented but really pluses up their ability to do strategic and operational planning," said Andrew F. Krepinevich, executive director of the Center for Strategic and Budgetary Assessments.

Defense Secretary Donald H. Rumsfeld expressed frustration about the Socom situation.