Violence surges with alien influx. Border violence is worsening as more illegal aliens pour into the US. This has increased pressure to reform laws on immigration, and it also highlights the controversy over giving some aliens `sanctuary.' (See related stories pages 4 and 8.)

Violence along the border is surging as the number of illegal immigrants entering the United States from Mexico hits new highs. It comes in two forms: attacks against the aliens, mainly by bandits, and assaults against Border Patrol agents themselves, usually by ``illegals'' resisting arrest.

``It is a very serious problem,'' says Alan Eliason, chief United States Border Patrol agent in the San Diego sector.

Criminal activity is increasing at many points along the border, from Texas to California. But the violence is most pronounced south of San Diego, a region one agent calls the ``Russian front'' of the US-Mexican border. This area is the main thoroughfare for illegal aliens heading north. Last year, the San Diego sector accounted for 36 percent of all illegals arrested along the US-Mexican border.

All this means more work for the Border Crimes Prevention Unit, a joint task force formed two years ago by the Border Patrol and the San Diego Police Department.

Antonio Ruiz, a member of the unit, has his bulletproof vest on and .38 pistol at his hip. He is ready for another night of trying to stop violence along this porous section of the border. The short, sturdily built Ruiz will spend the night with nine other officers walking a series of jojoba-studded canyons that separate Tijuana, Mexico, from this southern California town.

Ironically, their mission of thwarting border crime includes protecting illegal aliens slipping into the US from bandits seeking to rob them. But the agents themselves are often attacked by ``illegals'' resisting arrest.

In the first four months of fiscal 1986 (Oct. 1-Jan. 31), 43 assaults were reported against Border Patrol agents in the San Diego sector -- almost double the number in the same period a year ago. Throughout the Border Patrol's western sector, stretching from California through Arizona, 60 attacks have been recorded against agents in the first quarter of fiscal 1986, a 66 percent increase over last year.

Agents in Texas have been involved in three shooting incidents with aliens in the past year. The encounters underscore a disturbing trend: A growing number of immigrants being arrested along the border are armed with guns and knives.

``In the past, we would never arrest an alien [and find that he or she was] carrying a firearm,'' says an agent at the US Border Patrol's southern regional office in Dallas. ``Now it is quite common.''

Immigration officials attribute part of the increased violence to the sheer volume of illegals now entering the US. The Immigration and Naturalization Service estimates that as many as 1.8 million aliens will be arrested during 1986 -- a 50 percent jump over last year's record pace. Most of them will be unemployed Mexicans, driven to the US by economic woes at home.

Another contributing factor, officials say, is the increase in drug smuggling across the border, which has brought a corresponding increase in crime of all kinds.

A more frequent source of violence along the border, however, is the attacks by bandits against immigrants. Most of this activity occurs in a 10-square-mile area straddling San Ysidro and Tijuana. The area, a favorite route of illegals, is laced with grassy canyons that make good cover for the bandits. Typically, they work in groups of three or more and jump the aliens at night. The bandits, usually from the Mexican side, then scamper back across the border with their loot.

``The criminals now tend to be a little more vicious,'' says Mr. Eliason. He notes that some bandits, when attacking a group, will shoot one alien to let the rest know they mean business. There has also been a recent upswing in assaults against illegals by US residents in the streets of San Ysidro.

Last year, 176 robberies, 8 murders, and 15 rapes were recorded against aliens, mostly in the San Diego sector. But police say the numbers don't reflect the extent of the problem, because the illegals, fearful of being sent back across the border, often don't report crimes.

One factor contributing to the high number of assaults lately, some officers suggest, is the changing mix of aliens flooding across the border. In recent months, more families have been trying to enter the US. They make tempting targets for bandits, who like to prey on the most vulnerable groups.

Moreover, there has also been a surge in the number non-Mexican illegals crossing the border. Since many travel great distances, such as from El Salvador, they usually carry along many possessions.

``They tend to be a little bit better targets,'' says Arthur Palmer, a sergeant with the San Diego Police Department.

Nevertheless, the Border Crimes Prevention Unit, formed two years ago, seems to have put a dent in the problem. Local officials credit the 12-member force with holding down the number of attacks by bandits.