KARACHI, Pakistan – Adam Gadahn, the American-born spokesman for al-Qaida, has been arrested by Pakistani intelligence officers in the southern city of Karachi, two officers and a government official said Sunday.Gadahn appeared in a video urging US Muslims to attack their own country the same day.The arrest of Gadahn is a major victory in the US-led battle against al-Qaida and will be taken as a sign that Pakistan, criticized in the past for being an untrustworthy ally, is cooperating more fully with Washington. It follows the recent detentions of several Afghan Taliban commanders in Karachi, including the movement's No. 2 commander.Gadahn has appeared in more than half a dozen al-Qaida videos, taunting and threatening the West and calling for its destruction. A US court charged Gadahn with treason in 2006, making him the first American to face such a charge in more than 50 years. He could face the death penalty if convicted. He was also charged with two counts of providing material support to a designated foreign terrorist organization.He was arrested in the sprawling southern metropolis of Karachi inrecent days, two officers who took part in the operation said. A seniorgovernment official also confirmed the arrest, but said it happenedSunday. They spoke on condition of anonymity because they were not authorized to release the information.The intelligence officials said Gadahn was being interrogated byPakistani officials. In the past, Pakistan has handed over someal-Qaida suspects arrested on its soil to the United States. Gadahn grew up on a goat farm in Riverside County, California, and converted to Islam at a mosque in nearby Orange County.Hemoved to Pakistan in 1998, according to the FBI, and is said to haveattended an al-Qaida training camp six years later, serving as atranslator and consultant. He has been wanted by the FBI since 2004,and there is a $1 million reward for information leading to his arrestor conviction.The 31-year-old is known by various aliases including Yahya Majadin Adams and Azzam al-Amriki.Hismost recent video was posted Sunday, praising the US Army major chargedwith killing 13 people in Fort Hood, Texas, as a role model for otherMuslims. The video released Sunday appeared to have been made after theend of the year, but it was unclear exactly when."You shouldn'tmake the mistake of thinking that military bases are the onlyhigh-value targets in America and the West. On the contrary, there arecountless other strategic places, institutions and installations which,by striking, the Muslim can do major damage," Gadahn said, an assaultrifle leaning up against a wall next to him.Pakistan joined theUS fight against Islamist extremists following the Sept. 11, 2001,attacks, and several high-ranking al-Qaida and Taliban have beenarrested. But critics have accused the country of not fully crackingdown on militants, especially those who do not stage attacks inPakistan, all the time while receiving billions of dollars in US aid.Osama bin Laden is believed to be hiding somewhere in the country, most likely close to the Afghan border.Al-Qaidahas used Gadahn as its chief English-speaking spokesman. In one video,he ceremoniously tore up his American passport. In another, he admittedhis grandfather was Jewish, ridiculing him for his beliefs and callingfor Palestinians to continue fighting Israel. Dawud Walid, theexecutive director of the Michigan chapter of the Council onAmerican-Islamic Relations in Southfield, Mich., condemned Gadahn'scall for violence, calling it a "desperate" attempt by Al-Qaida'sspokesman to provoke bloodshed within the US.Walid, a Navyveteran, said Muslims have honorably served in the American militaryand will be unimpressed by al-Qaida's message aimed at their ranks."Wethoroughly repudiate and condemn his statement and what we believe arehis failed attempts to incite loyal American Muslims in the military,"he said.Imad Hamad, the senior national adviser for theAmerican-Arab Anti-Discrimination Committee, based in Dearborn, Mich.,condemned al-Qaida's message and said it would have no impact onAmerican Muslims."This is worthless rhetoric that is not going to have any effect on people's minds and hearts," he said.Appearingin 2006, in a 48-minute video along with al-Qaida's No. 2 leader, Aymanal-Zawahri, Gadahn called on his countrymen to convert to Islam and forUS soldiers to switch sides in the Iraq and Afghan wars.