Police have charged a 12-year-old boy with a Memorial Day graffiti attack in which the acronym for the Palestinian Liberation Organization was written on the homes of some Bay Ridge, Brooklyn, residents who were displaying American flags.

A police spokesman, Detective John Sweeney, described the boy only as “male, 12-years-old, Arabic.” He was charged with criminal mischief and making graffiti, misdemeanors that will be handled in family court.

On Memorial Day, patriotic residents of Senator Street between Fifth and Sixth avenues in Bay Ridge awoke to see the letters PLO painted on a garage, four trees, and a van. Only the houses on the block that displayed the American flag were attacked.

Tensions were already high among some residents of the area. On May 14, about 200 Brooklyn Palestinians marched through Bay Ridge in an anti-Israel protest. Many held up signs denouncing America’s support of Israel and chanted “Shame, shame, U.S.A.”

News of the arrest has done little to comfort many Bay Ridge residents, who perceive the political message allegedly sent by the 12-year-old as only a small piece of a growing cultural conflict resonating in the small corner of south Brooklyn.

Two local Internet discussion forums have become hotbeds of anger and frustration. One popular thread on Bayridge.com, “Anti-Americanism in Bay Ridge,” has received almost 2,000 hits in the last 30 days. Another, “That Cartoon that is getting the Muslims upset,” has received nearly 3,000 hits. On Bayridgetalk.com, one thread is titled: “Bay Ridge is a hot bed of terrorism.”

The tensions apparent in cyberspace also played out on the streets.

Out of fear of further retribution, members of one family living on Senator Street in Bay Ridge said they have stopped displaying the American flag. Other residents decided to leave Old Glory up, but not without hesitation.

“I believe they were trying to intimidate us,” a resident in one of the houses whose front yard tree was defaced by vandalism, Ayed Eskander, said. “They sent a message to six houses. Four of them on the tree, one on the fire drain, and one on a van. Only the homes that displayed the American flag were attacked. The homes that didn’t have the flags up were left alone.”

Bay Ridge has seen a rise in its Arab population over the past three decades and at times there have been signs of contentious relations with new Muslim immigrants.

According to some residents, the tensions with the Muslim community were at a boiling point during the days after the terrorist attacks of September 11, 2001, but have since cooled off.

Tensions resurfaced after the recent conviction of Shahawar Martin Siraj, 23, who was found guilty of a conspiracy to bomb the subway station near Macy’s at 34th Street. Police arrested Siraj and a co-conspirator just days before the city hosted the 2004 Republican National Convention.

Some in the Muslim community viewed the trial as proof that police tried to entrap and prosecute innocent Arabs.

Not everyone is convinced that the relationship between the Muslim community and other local residents is strained. But Mr. Eskander, who moved to Bay Ridge from Egypt in 1980 to “raise his children in freedom,” wonders whether the PLO graffiti is only the beginning.

The Egyptian-born Mr. Eskander also brought his flag inside, although for a fairly innocuous reason.

“I brought it in because it had a small tear,” he said. “I replaced it with a bigger flag. I want everyone to see it. That is my flag now and this is my country.”