As the Costa Rican government sees it, the recurrent incidents on the border with Nicaragua are diversion tactics employed by President Anastasio Somoza to create an international untenable situation at home.

In the latest incident, on Tuesday, Costa Rica accused Nicaraguan forces of crossing the border and killing two civil guardsmen. Costa Rica then broke relations with Somoza's government.

As Somoza has increasingly charge Costa Rica with harboring Sandinista guerrilla training camps in border areas, high officials here were known to fear a full-fledged Nicaraguan invasion.

In an interview last week following another Nicaraguan incursion - two helicopters landing on the Costa Rican side of the border - costa Rican Minister of Security Juan Jose Echeverria said, "We see a clear objective on the part of the Nicaraguan government to provoke us. So far we have reacted with great caution."

But the repeated Nicaraguan incursions into a defenseless Costa Rica - it has no army but only a 5,000-man civil guard - are thought here to be part of a design to force an international peacekeeping force to take up positions along the border.

Such a force would make it more difficult, if not impossible, for the Sandinista guerrillas to operate in the area. In the view of these analysts, it would suit not only Somoza, who is expecting a broad new guerrilla offensive, but also the United States. The force could give Washington more time in its effort to pressure Somoza to resign, Staving off a new offensive by the guerrillas that could give them a major voice in any post-Somoza government.

The decision by the Organization of American States on Wednesday to send border observers could serve the same purpose.

Although Costa Rican President Rodrigo Carazo, in an interview, denied the existence of Sandinista training camps on his territory, Costa Rica's civil guard has been patrolling the border with greater intensity and launched an "operation cleanup."

According to the Security Ministry, about 200 Sandinistas have been picked up and sent to Panama or Venezuela recently.

At the same time, Security Ministry sources said, said eight Somoza agents have been aprehended aand handed over to the Somoza government. According to one official, they were checking Sandinista movements while two of them "were part of a squad to assassinate Sandinista leaders" believed to be here.

The Security Ministry sources said that as the situation between the two countries were growing more tense and a new guerrilla offensive seemed near, the U.S. Central Intelligence Agency also had stepped up its activity in Costa Rica.

The Nicaraguan conflict is having broad repercussions in this republic of 2.1 million persons which as a functioning democracy, is a virtual island in Central America.

At least 30,000 Nicaraguans have fled here since the brief September civil war, including many supporters of the Sandinista National Liberation Front.

Although Carazo has repeatedly said "our best defense is that we have to be pushing peaceful Costa Rica into an arms race. The government is currently negotiating the purchase of ten 20mm cannons - for both anticraft and antitank use - from Israel, which is also Somoza's main arms supplier at present.

Costa Rica envoys traveled to Venezuela on Wednesday for urgent consultations with President Carlos Andres Perez about the need for Venezuelan military help. Costa Rica signed a defense pact with Venezuela in September following a Nicaraguan incursion. Five Venezuelan warplanes and four Panamanian helicopters are stationed at san Jose's airport.

The country is said to have only three absolete helicopters and six unarmed patrol boats of its own.

But in recent weeks private arms dealers from the United States, Switzerland, Belgium, Spain and Brazil have arrived.

"We have absolutely no plans to start an army, but they've offered us everything from light arms to planes and tanks," the minister of security said.