WASHINGTON -- Former Sen. Rick Santorum said Tuesday that Sen. John McCain, who spent 5 1/2 years enduring brutal treatment at the hands of his North Vietnamese captors, doesn't know how effective waterboarding and other harsh interrogation techniques can be. The Republican presidential contender insisted the tactics led the United States to al-Qaida leader Osama bin Laden.McCain, the top Republican on the Senate Armed Services Committee, said in a speech last week that waterboarding al-Qaida's No.