WASHINGTON -- The Department of Defense's responsibilities have grown beyond anything that military commanders had imagined at the end of the Cold War, according to national security specialists; some have voiced worry that the department's expanding roles could tax the Pentagon's resources or compromise some civilian authorities.

Nearly 15 years after the fall of the Berlin Wall, there is no more talk about a budgetary ''peace dividend'' or trimming US forces. The US military is not only operating in more places around the world than at any other time since World War II, but it has also expanded into areas previously reserved for other government agencies: establishing a new intelligence unit, launching a homeland defense command, and exerting growing influence in foreign policy.

''You've got people doing things, certainly from the Pentagon perspective, that they wouldn't have dreamed of 15 years ago or even 10 years ago,'' said Andrew F. Krepinevich, a former Defense Department official who runs the Center for Strategic and Budgetary Assessments, a defense policy institute.

While it has become fashionable to ascribe the expansion to the ambitions of Secretary of Defense Donald H. Rumsfeld, its roots are more complex, growing out of long-term trends that began with the end of the Cold War and from the response to the Sept. 11, 2001, terrorist attacks.

Some national security specialists worry that this expansion could hurt US policy and the military itself. Even with Bush budget increases, including a requested $15 billion this year, the military can handle only so many missions at a time.

For example, while George Bush campaigned in 2000 against using the military for nation building, US forces have subsequently assumed that sort of mission in Afghanistan and Iraq.

''Certainly through the 1990s, as we found ourselves in these lower-level conflicts that you would not term as world wars, but to look at the Kosovos or the Bosnias or the Afghanistans, we are putting the military right on the edge of political roles,'' said Tad Oelstrom, a retired three-star Air Force general who heads a national security program at Harvard University's Kennedy School of Government.

Oelstrom said that, in many cases, the US military's role in other countries has increased beyond defense-related activities. ''The military all along has wondered whether or not they are prepared to do this and what they should do or shouldn't do,'' said Oelstrom.

Some specialists worry that as the military is used, other traditional instruments of foreign policy can suffer and atrophy. The State Department, they fear, could be undercut, and the intelligence community could become distorted and politicized.

''You've got many different tools of national power, and if you've got one that is very muscular and well developed, and you have others that in comparison are a bit more anemic . . . you have a tendency to use the one that's well-developed,'' said Clark Murdock, a former defense official who works at the Center for Strategic and International Studies.

The newly created position of undersecretary of defense for intelligence underscores the changes in progress at the Pentagon. Rumsfeld said the post would not duplicate the Defense Intelligence Agency, the Central Intelligence Agency, the National Security Agency, or other members of the intelligence community.

Stephen Cambone, the new undersecretary, said last month that the existing agencies ''will all go about doing their tasks,'' but that his unit will ensure that they are meeting the intelligence needs laid out by the Pentagon.

The mission, he said, ''is to try to get to them a sense of what the priorities are for the department.''

But the office's mandate was drawn broadly, giving Cambone direct control over the Defense Intelligence Agency and National Security Agency as well as the National Reconnaissance Office and the National Imagery and Mapping Agency.

Those agencies are officially part of the Department of Defense, answering both to Rumsfeld and CIA Director George Tenet. But giving Cambone explicit authority over the agencies allows him far-reaching authority that intelligence specialists said cuts into a major piece of Tenet's turf.

Jay Farrar, a former employee in the Defense Department and National Security Council who works with the Center for Strategic and International Studies, said that Cambone's broad authority is not a coincidence. ''It's one more step in the Defense Department seeking to consolidate major control over the intelligence apparatus of the United States,'' Farrar said.

The fear is that giving the Pentagon greater influence will politicize the intelligence process by encouraging reports that support current policies, rather than reporting trends and developments that challenge them. ''It looked like a classic case of you can't get the intelligence you want from the intelligence community, you create your own unit,'' said Mel Goodman, a former CIA analyst who teaches at the National War College and is a senior fellow at the Center for International Policy. ''The civilian side of the intelligence community gets weaker and weaker, and it's obvious that Rumsfeld's playing a policy game to get intelligence to support policy.''

Complaints about the quality and availability of intelligence during the first Gulf War prompted a decadelong military effort to gain more influence over the gathering and disseminating of intelligence. Rumsfeld has been a critic of the intelligence community since chairing a 1998 commission that examined national missile defense. Some analysts argue that the reform was needed. ''It is an iteration of how to organize intelligence to get us better information,'' Oelstrom said.

The Pentagon's growing profile extends beyond intelligence. The end of the Cold War opened swaths of the globe into which the US military has become engaged or more deeply enmeshed, especially in Eastern Europe, Southeast Asia, Africa, and the Middle East. Current US military operations include Iraq, Afghanistan, the Horn of Africa, Colombia, the former Yugoslavia, South Korea, the Philippines, and former Soviet states such as Georgia.

In the process, regional combatant commanders have gained a stature that, in many cases, overshadows the role of ambassadors in the regions. The military commanders have greater resources, bigger staffs, and better access to intelligence than ambassadors serving in the same countries.

''Part of the reason why a regional combatant commander has such prestige throughout a region is if he visits a country, has an entire entourage, [he] is the manifestation of American power in a way that an individual diplomat isn't,'' Murdock said.

That has been exacerbated by Rumsfeld's activist view of the defense secretary's role in formulating foreign policy, often behind the scenes in frequent missives -- ''Rummygrams'' -- to Secretary of State Colin L. Powell and others.

Rumsfeld and Powell ''have strong personalities, but they aren't necessarily on the same page, which I think is good, not bad,'' said Oelstrom, who argues that competing ideas and visions can yield a balanced foreign policy. But potential problems lie in over-reliance on the military for foreign policy, according to Murdock and others.

One new job for the military is the Pentagon's evolving role in homeland defense. Since the Sept. 11 terrorist attacks, the Pentagon has added an assistant secretary for homeland defense and last year created a northern command to coordinate the military response to domestic threats.

Though it can occasionally be called upon to support civilian authorities in times of major need or disaster, the military is constitutionally barred from law enforcement in the United States. The creation of the command has raised the specter for some that that division is eroding.

''There are two views on it,'' said Michael Greenberger, director of the Center for Health and Homeland Security at the University of Maryland. ''One is that it's very scary that we now have the military trying to play what has traditionally been a civilian, domestic, non-DOD role. But . . . I don't think anybody really can make an assessment about what's going on right now.''

Globe Correspondent Bryan Bender contributed to this report.

© Copyright 2003 Globe Newspaper Company.

###