The Blue Berets and the Tridents, suited up in combat fatigues, get together on weekends to practice such martial skills as firing automatic rifles, crawling under barbed wire and marching in formation.
Both groups belong to the Free Costa Rica Movement, a right-wing organization that regards the revolutionary Sandinista government of neighboring Nicaragua as a dangerous enemy. They are preparing to meet what they call "the Nicaraguan threat."
The conservative fringe is not the only segment of Costa Rican society that is worried about the dangers across the border. Anti-Sandinista sentiment is stronger and more widespread here now than at any other time since the Marxist-led revolutionaries seized power in Nicaragua nearly six years ago.
"It's definitely higher than it has ever been," a Western diplomat said of the anti-Sandinista fervor. "It's at its peak."
In July, 1979, when the Sandinista guerrillas overthrew Nicaragua's President Anastasio Somoza, the Sandinistas' support in Costa Rica was nearly unanimous.
The welling anti-Sandinista feeling was strengthened May 31 when two members of Costa Rica's Civil Guard were killed and nine others wounded near the border with Nicaragua. Nicaragua blamed the incident on anti-Sandinista guerrillas who operate along the border, but Costa Rica said its policemen were victims of an unprovoked attack by Nicaragua's Popular Sandinista Army.
On June 11, right-wing saboteurs blasted a pylon supporting electric power lines in northern Costa Rica to protest the attack and the sale of Costa Rican electricity to Nicaragua. The day before, demonstrators stoned the Nicaraguan Embassy in San Jose.
The demonstrators were led by members of the Free Costa Rica Movement, including Bernal Urbina. Urbina, 47, a lawyer with a sparse blond mustache, is the movement's president.
"In the face of Nicaraguan aggression, the Costa Rican people cannot be expected to remain peaceful," Urbina said after the attack.
'Have Grown Incredibly'
In an interview, he refused to say how many members the Free Costa Rica Movement has--"Why should we let the enemy know how many we are?"--but he said that increased anti-Sandinista sentiment has stimulated growth.
"We have grown incredibly under the Nicaraguan threat," he said.
The movement's Blue Berets group gives military training to members who are 18 to 23 years old, and the Tridents to those 23 to 35.
"This type of activity has been intensified because of the Nicaraguan threat," Urbina said, adding that the Blue Berets and Tridents will be ready to fight under government supervision "in case of an attack by Nicaragua."
The movement was founded in 1961 as a bulwark against the spread of Cuban-style revolution. Although its membership rolls are secret, Public Security Minister Benjamin Piza has acknowledged being a founder. Piza, a member of the governing National Liberation Party, is responsible for Costa Rica's Civil Guard, the national police force.
Getting U.S. Training
Costa Rica has no army, but under Piza, the Civil Guard is receiving military training from a U.S. Army Special Forces team.
Communist Congressman Arnoldo Ferreto asserts that the Reagan Administration is using economic aid to Costa Rica as a lever to push the government into an increasingly anti-Sandinista position. He said that President Luis Alberto Monge complies "so that Reagan will continue giving handouts.
Monge on Friday accepted a call by Nicaragua for internationally supervised talks to ease tension on their border, the Reuters news agency reported. He told Nicaraguan President Daniel Ortega in a letter that he approves the idea of talks as long as they do not hinder peace efforts by the Contadora Group of Latin nations.
Ferreto, who is president of the Moscow-line Popular Vanguard Party, said the United States supports the Free Costa Rica Movement.
"They are the spoiled children of the Yankee embassy," he said.
George Jones, charge d'affaires at the U.S. Embassy, said that the embassy has no connection with the movement.
"The United States provides no assistance (and) has no relationship of any kind with the Free Costa Rica Movement, other than occasionally seeing them at large parties," Jones said.
Fred Morris, the American editor of a left-leaning newspaper here, blames a steady campaign by Costa Rica's conservative press for turning public opinion against the Sandinistas.
"Ninety-five percent of the people have been encouraged into this right-wing hysteria," Morris said the other day.
Information Minister Armando Vargas said that the movement is not a significant political force.
"As we say here, a barking dog doesn't bite--and they bark a lot," Vargas said.
He noted that the Costa Rican National Party, which represents the far right on the country's political spectrum, received less than 2% of the vote in the 1982 elections.
The country's two main political parties, the National Liberation Party and the Social Christian Unity Party, are generally middle-of-the-road.
But Vargas said concern over Nicaragua has given a conservative, anti-Sandinista tone to the campaign that has started in anticipation of next February's presidential and congressional elections.
Shift to Right Seen
"There has been a shift to the right in the whole political debate," Vargas said. Many candidates, he went on, appear to be competing to see "who sounds more like President Reagan and who is tougher on the Sandinistas."
The main source of tension between Nicaragua and Costa Rica has been the border area, where the anti-Sandinista guerrillas of the Democratic Revolutionary Alliance are based. The alliance, known as ARDE after its initials in Spanish, is headed by former Sandinista hero Eden Pastora. A larger anti-Sandinista group, the Nicaraguan Democratic Force, is based at the opposite end of Nicaragua, on the border with Honduras.
Nicaragua complains that ARDE uses Costa Rican borderlands for refuge and military staging, while Costa Rica charges that the Nicaraguan army has repeatedly violated Costa Rican territory.
In May, the Sandinista army began an offensive aimed at clearing the guerrillas from along the San Juan River, which defines the border for about 80 miles. ARDE forces, short on ammunition and supplies, retreated from four riverside camps, including Pastora's command headquarters at La Penca. It was at the height of the offensive when the two Costa Rican Civil Guardsmen were killed.
Since that incident, Nicaragua has revived a proposal for creating a demilitarized zone along the river. But President Monge said that Costa Rica has no need to demilitarize its side because this country has had no army since 1948.
Jose Davila, ARDE's political coordinator, said the Sandinista army has gained control of about 25 miles of territory on the San Juan River. He said the rebels still control the river east of La Penca to the Caribbean, about 55 miles.
"We stopped the Sandinista offensive at La Penca," Davila said.
He said the Sandinistas had hoped to eliminate the ARDE rear guard along the river, cutting supply lines to rebel troops deeper within Nicaragua.
By removing rebels from the border, Nicaragua would also reduce a potential source of friction between the two countries.
Leonor Arguello, Nicaragua's ambassador to Costa Rica, said the Sandinistas plan to create unilaterally a demilitarized zone three miles deep along the river on the Nicaraguan side of the border. The zone would be patrolled by an international peacekeeping force, she said.
Arguello said the border attack and the later stoning of the Nicaraguan Embassy were part of a "well-orchestrated campaign" against the Sandinistas.
"Behind it is a mandate from the United States to cause problems between this country and Nicaragua," she said. "It is to make believers of the Costa Rican people so that they will happily accept the coming of American military forces under the pretext of protecting Costa Rica from Nicaragua."
A newspaper columnist, Enrique Vargas Soto, is already a believer. He has written that the installation of an American base in Costa Rica is the only effective way to safeguard the country from "the communist boot of Nicaragua."