A Pentagon in the West, this city is a stellar watchdog

It's an ordinary black multiline telephone, with a red hold button. It sits on a console labeled ''CINC/NORAD'' - commander in chief, North American Aerospace Defense Command.

If the Soviet Union were ever to launch a nuclear missile at the United States, this would be the phone over which military leadership would advise the president of the United States on whether to push the button.

This control room, the NORAD Command Post, is deep inside ''the mountain'' - the Cheyenne Mountain Complex on the south side of Colorado Springs.

It's a scene that has been mocked up so many times in movies - or at theme parks, for that matter - that it's a bit unreal to be standing there at the armchair labeled ''CINC/NORAD.''

There are three tiers of consoles with computers facing two huge screens as theater balconies would face a stage. The big screens, showing test patterns at the time of this reporter's visit, can repeat the displays of the smaller computer screens at each console.

What the computers show is a world map, with the possibility of indicating trajectories of missiles being launched anywhere in the world. At the top tier is a two-member team of civilian employees of the Federal Emergency Management Agency, who would be interested in tracking, say, a major piece of space junk coming in for an unforeseen landing on Nebraska.

The middle tier, reserved for the NORAD commander in chief and his deputies, is usually empty except for crisis situations. At the bottom level at any given time is one of five brigadier generals (two from the US Army, two from the US Air Force, and one from the Canadian Air Force, since NORAD is a joint command) and the several members of his team, providing routine space surveillance of the globe. The information they work with comes from orbiting satellites and from radars scanning the northern approaches to North America, including facilities in Thule, Greenland, and Fylingdales, in northeastern England.

Above the huge screens are two scoreboards, so to speak, one for the Western Hemisphere and one for the East. These record missiles launched but ''not yet impacted'' (NYI, acronymically), plus those ''IMP'D'' (impacted), plus ''TTG'' (time to go) estimated for the former group. Remember where you heard it first.

The command post is the heart of a 15-building ''city'' in the middle of a 100 million-year-old granite mountain. Some 2.8 miles of tunnel were blasted out when the complex was under construction during the early 1960s.

Cheyenne Mountain was chosen for its granite solidity, plus its distance away from the Soviet Union. The presence of Fort Carson and the Air Force Academy as support facilities was also a factor. ''The mountain'' holds periodic ''button up'' exercises, as the expression goes, in which it functions as a closed-up fortress on its own for 30 days at a time, as it would have to in war. The complex is deemed ''safe from all but a direct hit by a multimegaton warhead,'' according to an official release.

Some 1,400 people - military and civilian, US and Canadian - work in the complex, with some 500 there during the day, and 250 for each of the other two shifts. Activities here include tracking satellites and space junk, such as a Hasselblad camera that was in orbit for a while after it was left there by some astronauts.

The Cheyenne Mountain Complex has been in operation since 1966; for 10 years before that, NORAD tracked satellites and missile launches from Ent Air Force Base in Colorado Springs, now site of the US Olympic Training Center.

But NORAD's ''star wars'' are just one aspect of the military presence in Colorado Springs. Long before the city started its campaign to draw in the electronics industry, it had been recruiting military facilities - to lessen its economic dependence on tourism. Today, the defense industry accounts for over $ 634 million in direct payroll.

The first big fish was Camp Carson, established as a training center during World War II, and now, promoted to Fort Carson, the home of the Fourth Infantry Division (Mechanized). A municipal airport also became Peterson Air Force Base.

Then, in the 1950s it was the US Air Force Academy, another story of how the whole city pulled together to grab the brass ring in the face of fierce competition. There were originally 582 sites proposed, with some degree of seriousness, for the academy. (This works out to one for every member of Congress, and then some.)

A bit of folklore circulates about how the Springs' quest began. One of the community leaders, Joseph Reich, was leafing through a newspaper as he sat in a barber chair when his eyes fell on a story that an academy was to be established - whereupon he decided that the Springs should enter the race.

''Is that a true story?'' Thayer Tutt, another community leader, was asked. He was co-chairman of a Colorado Springs group formed to woo the committee that was to select a site for the academy. That committee included such luminaries as Charles A. Lindbergh.

''I think that's true. Mostly true, anyway,'' Mr. Tutt replies, hesitant to let the facts interfere too much with a good story.

The same sort of campaigning was needed to win the latest plum - the Consolidated Space Operations Center (CSOC). It will monitor and control all US military activity in space - the military missions of the space shuttle, in the first phase, and military satellites, in the second.

Some $67 million has been approved by Congress for construction on the center , at a site near Peterson Air Force Base, during the fiscal year beginning Oct. 1. It will ultimately employ some 1,800 people, one-third of them military and two-thirds a mix of Air Force civilians and contractor staff.

Kirtland Air Force Base in New Mexico had been another prime candidate to get CSOC, with Sen. Harrison H. Schmitt (D) of New Mexico, himself a former astronaut, leading the charge. But with NORAD and the Air Force Academy, the defense-related electronics firms, plus supporting facilities in nearby Denver, Colorado Springs and the snowball effect won out.

Another Air Force consolidation move expected to be a big plus for the Springs is the creation of Space Command (not to be confused with the Space Operations Center), as of this Sept. 1. This command, linking various Air Force space operations, will be built around the US aerospace defense staff of NORAD and will entail the transfer of some 200 people from Offutt Air Force Base in Nebraska.

But even though Colorado Springs continues to win such plums from the military, the drive to diversify the economy has not weakened.

A strong military presence is generally regarded as a big help in ''recession proofing'' a local economy. But James Hill, former NORAD commander in chief and president of the local chamber of commerce, sees some installations as less immune to US cutbacks than others.

As long as the United States has an Air Force Academy, it will stay in Colorado Springs, and NORAD is unlikely to be moved. ''Not too many other places have a granite mountain you could just drill a big hole like that into,'' he observes.

But the time could come when Peterson Air Force Base, the support base for the Cheyenne Mountain Complex, may not be essential.

And there's already been a close call at Fort Carson. The fort's mission is the training of Army tank crews. Some time back, it was determined that more land was needed to fulfill this mission. As it happened, the Army was able to buy more land adjacent to its existing property. But, Mr. Hill reports, if no land had been available, there would have been no alternative but to move the fort - with serious repercussions for the local economy.

Frank O'Donnell, local economic development chief, concurs, ''A base closure would have a devastating effect.''

Despite the community's desire to diversify, one hears again and again, ''The military is well integrated into the community.'' Others add, ''It's a conservative, pro-military town. But conservative doesn't mean redneck, though.''

The military presence in Colorado Springs is after all a pretty elite one. It doesn't mean soldiers hanging out on street corners Saturday afternoon so much as it means having a retired commander in chief of NORAD as president of the chamber of commerce. Mr. Hill points out that the city's military heritage goes back well before Fort Carson. The town was founded in the 1870s by an active Army general, William Palmer, at a time when the Army Corps of Engineers was an active force in the West, building dams and railroads.

John Tagert, Colorado Springs police chief, cites an example. The NATO defense ministers were originally scheduled to meet in San Francisco last March. But fearing there would be too many protest demonstrations there, they opted for a change of venue: to the Broadmoor Hotel in Colorado Springs.Even here, there were some protesters, the chief says. ''We met with them beforehand, and we gave 'em a place to demonstrate - because we were afraid they'd get hit if they were out in traffic. And there were a few token demonstrators when they actually had the meeting, but it was no big deal.''

The fact that NORAD is a joint US-Canadian operation helps makes the Springs a bit more cosmopolitan: Many Canadian officers posted at NORAD like the area so much they decide to retire here.