The Border Patrol has finished installing razor-sharp barbed wire atop a 5-mile stretch of fence on the Mexican border, an addition critics call heavy-handed and an eyesore.

Agents say the concertino wire on a violent stretch separating San Diego from Tijuana, Mexico, has already contributed to a sharp drop in attacks by assailants hurling rocks, bricks and sometimes even exploding bottles of gas.

"The effects have been phenomenal," Michael Corley, head of the Border Patrol's Imperial Beach station, said at a news conference Tuesday after a crew installed the last piece of wire.

Without the wire, migrants could jump the fence in only 15 seconds. But it now takes several minutes for them to cut a hole in the fence using handheld, battery-powered saws, Corley said.

Mexico's consul general in San Diego, Remedios Gomez Arnau, said efforts by Mexican authorities to prevent attacks on border agents may explain the drop in violence, not the razor wire. She said the Border Patrol rejected her plea to reconsider installing the wiring.

The 5-mile stretch is the only place on the U.S.-Mexico border with razor wiring on top of the fence, and there are no plans to use it elsewhere, said Border Patrol spokesman Lloyd Easterling.

The fence blocks a hardscrabble Tijuana neighborhood where the Border Patrol began firing tear gas and powerful pepper-spray weapons last year in response to Mexican assailants. Innocent families were caught in the melee.

The counterattacks have diminished, according to the Border Patrol, as the more formidable fencing appears to have pushed border crossers elsewhere, heralding a welcome calm for many who live in the shanties.

The United States "is just protecting its private property," said Tijuana resident Jose Arias Martinez, 75, whose pregnant daughter-in-law fainted last year when tear gas fired by the Border Patrol seeped through his walls. "If I had the money, I would build a fence around my home, too."

Jose Ramirez, 58, said the razor-wire fence that he can see from the kitchen window of his Tijuana home will only push migrants to less guarded — and more dangerous — terrain.

"It's very ugly," said Ramirez, who keeps a tear gas canister from last year's attacks amid the cactus in his backyard. "How sad that it has come to this."

Homeland Security Secretary Michael Chertoff said last month that attacks on agents were an "unhappy" consequence of heightened enforcement. The Border Patrol said its agents were attacked 1,097 times during the fiscal year that ended in September, an 11 percent increase from 987 a year earlier.

Many occurred in the San Diego area, but the Border Patrol said attacks dropped in the 5-mile stretch where the razor-wire was installed. It counted 90 attacks on agents in the 11 months after installation began Dec. 17, compared to 184 in the preceding 11 months.

Apprehensions in the 5-mile stretch dropped 53 percent during that time to 3,746 from 7,989, the Border Patrol said. Corley said the fencing has pushed migrants west toward the Pacific Ocean — and resulted in more attacks against agents in that area.

Enrique Morones, founder of Border Angels, a group that assists migrants, said the wiring resembles the Berlin Wall and reminds him of thousands of migrants who have died trying to cross the border.

"The razor wire is immoral, it's wrong, and it symbolizes the worst of the American spirit," he said.