Hezbollah, the Iranian-backed Shiite group, has established a significant presence in Iraq, but is not taking part in attacks on American forces inside the country, according to current and former United States officials and Arabs familiar with the organization. Iran is believed to be restraining Hezbollah from attacking American troops, and that is prompting a debate within the Bush administration about Iran’s objectives, administration officials said. Hezbollah’s presence has become a source of concern as it is recognized by counterterrorist experts to have some of the most dangerous operatives in the world. Full Story