The Pentagon is launching an urgent review of whether military procedures hinder the identification of servicemembers who pose a threat to their fellow troops.

Along with that 45-day examination, Defense Secretary Robert Gates also ordered yesterday an in-depth investigation, lasting four to six months, into whether Army policies and procedures played any role in failing to prevent the Fort Hood shootings.

Word of the Pentagon reviews came on the same day as a Senate committee held the first public hearing into the attack that killed 13 people and wounded dozens of others at the Army post.

Homeland Security and Governmental Affairs Chairman Sen. Joe Lieberman, an independent from Connecticut, began the hearing by saying that he believed the incident was "a terrorist attack." He added that senators wanted "to determine whether that attack could have been prevented, whether the federal agencies and employees involved missed signals or failed to connect the dots."

As more becomes known about the behavior ahead of the shootings of Maj. Nidal Hasan, the alleged gunman, pressure has mounted on the Obama administration and the military to explain why the Army psychiatrist didn't warrant further investigation or preemptive action.

U.S. intelligence officials knew last year that Hasan had been corresponding with a radical Islamic cleric; earlier this year investigators learned of internet postings, allegedly by Hasan, that indicated sympathy of suicide bombers; and colleagues of Hasan's at Walter Reed Army Medical Center said the "intensity" of his embrace of Islam raised concerns among doctors there.

Gates said the Army's "in-depth, detailed assessment" would look at "whether the Army programs, policies and procedures reasonably would have prevented the shooting." The goal, he said, is "to determine whether, in fact, there were lapses or problems."

The secretary promised "full and open disclosure" of the findings of the reviews, adding that avoiding "similar tragedies" is imperative.

Togo West Jr., the former Veterans Affairs secretary and army secretary, and retired Adm. Vernon Clark, a former chief of naval operations, will lead the 45-day review. It will look for "deficiencies" in Pentagon procedures for "identifying servicemembers who could potentially pose credible threats to others," Gates said.