Washington - The failed bombing in New York's Times Square is a possible signal that militant leaders in Pakistan have shifted their focus to targets in the U.S. and other Western countries instead of sticking to their home base, according to U.S. counterterrorism officials.

The attack, they also warned, could be only the first by terrorist groups that seek to avoid detection by using simpler methods that are more independently planned. The officials spoke on condition of anonymity because they were not authorized to discuss the case publicly.

U.S. investigators and intelligence agencies are trying to establish whether accused bomber Faisal Shahzad was trained or recruited for the Times Square operation by any Pakistan-based terrorist organization, including the Pakistani Taliban. Shahzad, a U.S. citizen of Pakistani descent, spent five months in Pakistan before returning to the United States in February and preparing his attack.

Shahzad has told investigators that he trained in the lawless tribal areas of Waziristan, where both al-Qaida and the Pakistani Taliban operate. He was arrested aboard an Emirates Airlines jet in New York just minutes before it was scheduled to take off for Dubai.

A senior military official told The Associated Press that investigators believe Shahzad had bomb-making training in Pakistan, sponsored in part by elements of the Pakistani Taliban.

If those suspicions prove correct, it suggests that groups based in Pakistan, including the Taliban along the Afghan border, may be taking on a more global approach after years of focusing attacks largely on government or coalition forces in their region.

That focus could stem from the Taliban's continued close association with senior al-Qaida leaders, who are believed to be hiding in the lawless regions on the border of Pakistan and Afghanistan, said one former Obama administration official, who spoke on the condition of anonymity because the investigation is continuing.