CAIRO - (AP) - Al-Qaida vowed to keep fighting the United Statesand avenge the death of Osama bin Laden, which it acknowledged forthe first time Friday in an Internet statement apparently designedto convince followers that it will remain vigorous and intact evenafter its founder's demise. Al-Qaida's plots are usually large-scale and involve planningover months or even years. But Western intelligence officials saythey are seeing increased chatter about cheap, small-scale attacks- perhaps by individuals or small extremist groups inspired to takerevenge for the killing. "USA, you will pay!" chanted more than 100 participants in apro-bin Laden protest outside the U.S. Embassy in London on Friday. A Western intelligence official said no concrete threat hasemerged so far that authorities considered credible. "There havebeen mentions of shootings, bombings and random violence, though itis not surprising, given bin Laden's death," the official said,speaking on condition of anonymity. Authorities in the U.S. and Europe chose not to elevate threatlevels. Interpol has asked law enforcement agencies in 188 countries tobe on alert for retaliatory attacks. Communities have been warnedto report anything suspicious. Embassies and some Americanbusinesses have added new security measures. Despite the Internet chatter, reaction in the Islamic world tobin Laden's death has been relatively muted compared with the ragethat he long inspired, raising questions about his relevance in theMiddle East - a region that has been changed by a wave ofpro-democracy uprisings. The al-Qaida statement, entitled "You lived as a good man, youdied as a martyr," did not name a successor to bin Laden. Hisdeputy, Ayman al-Zawahri, is now the most prominent figure in thegroup and a likely contender to take his place. Although the statement's authenticity could not be independentlyconfirmed, it was considered to be authentic. It was posted onmilitant websites Friday by the al-Fajr Center, al-Qaida's onlinemedia distribution network, and the writing style was typical foral-Qaida. The statement was issued in the name of theorganization's General Command and dated Tuesday, the day after binLaden's death. White House press secretary Jay Carney said U.S. officials areaware of the statement and the threat. "What it does obviously isacknowledge the obvious, which is that Osama bin Laden waskilled," said Carney. "We're quite aware of the potential for(terrorist) activity and are highly vigilant on that matter forthat reason." There had been hope that bin Laden's death would cause theAfghan Taliban to rethink its ties with al-Qaida - a union the U.S.insists must end if the insurgents want to talk peace. Thefoundation of their relationship was believed to be rooted in binLaden's long friendship with the Taliban's reclusive leader, MullahMohammed Omar. But on Friday, the Afghan Taliban issued a statement saying binLaden's death will only boost morale among insurgents fighting theU.S. and NATO. The Taliban praised bin Laden for his sacrifice in the Afghanwar against the Soviets in the 1980s and said anyone who believeshis death will undermine the current conflict is displaying a"lack of insight."