A mini-arms-race and military buildup is under way throughout Central America. Governments throughout the region are beefing up their military arsenals and in the process spending millions of dollars - an estimated $100 million in 1981. Even more is ticketed for 1982.
''The (arms) race is a bit like a fire out of control,'' says a foreign military specialist here. He adds: ''It is sweeping the area.''
And it is bound to increase the tensions already evident in the region. Although Central America has only some 22 million people, its volatility is evident in the civil war under way in El Salvador and the recent war in Nicaragua.
The military buildup began with the victory of Nicaragua's Sandinista guerrillas in 1979. But it was Nicaragua's acquisition of heavy Soviet tanks earlier this year that sparked an arms race throughout Central America.
Nicaragua's neighbors are scrambling for costly and sophisticated weaponry, including missiles and antitank weapons. Critics in each country argue that these sums should be used on education and housing, but they are being ignored.
The arms race is proving to be a field day for arms merchants, including Belgians, Brazilians, and Israelis, who are regularly seen in hotels throughout Central America.
Although purchases of military equipment, including items for local police forces, are shrouded in secrecy, there is no mistaking the military buildup:
* Nicaragua received those Soviet tanks, an estimated 100 T-54s and T-55s, early in the summer. The only heavy tanks in Central America, these are of post-World War II vintage and can mount a 100-mm cannon. They were supplied by Cuba and perhaps by Algeria.
Acquisitions of other weapons are now in the works or contemplated. The Soviet Union and friendly Arab nations are the suppliers. The value of these weapons is thought to be around $150 million, but whether Nicaragua is being asked to pay for them is unclear.
* Honduras, which borders on Nicaragua, wants to buy sophisticated jet aircraft and is also shopping around for a tank to counter the Soviet tanks next door. It is negotiating with the United States for the purchase of Northrup F-5s to replace its 1950s vintage US-made F-86F Sabre fighter planes and French Mystere transport planes. It also has raised its military spending by 25 percent this year, using the increase for small arms and ammunition. The cost of the additional weaponry already purchased is $20 million.
* Guatemala, with by far the best Army in the area, also wants sophisticated jet fighters, and is particularly interested in General Dynamics' well-received F-16. It has begun talks with the Reagan administration on the issue. Equally important, it made substantial new purchases of weapons from Israel, long its biggest weapons supplier, for $20 million this year. Brazilian weapons are being tested by the Guatemalan Army and it is understood that an order for some of these arms may be coming.
* El Salvador, locked in a stalemated civil war, wants to acquire up to $150 million worth of US military equipment, substantially more than this year's estimated $35 million, and is about to embark on a strengthening of its Army from 12,000 men to perhaps as many as 20,000. A budget increase for such strengthening is under study.
* Costa Rica, which has no army and relies instead on a 5,000-member civil guard, is increasing its spending for ''public safety'' by 20 percent this year and is considering a further increase next year. It has upgraded guardsmen's pay scales by 15 percent this year, with more planned for next year. The cost: an estimated $13 million.
* Panama, also without an army but with a well-equipped and trained National Guard, may soon look for new weapons, but it feels less urgency than some of the other nations in the region. It has long relied on the US military presence in the Panama Canal, but with the US role phasing out, a military buildup by Panama is regarded as likely.