Before Deadly Bulgaria Bombing, Tracks of a Resurgent Iran-Hezbollah Threat - By Sebastian Rotella

After a decade in which al Qaeda dominated the world stage, the global terror threat from Iran has escalated sharply, generating a swarm of recent plots from Delhi to Mombasa to Washington and signaling an aggressive new strategy, counterterror officials say.

But there were meager results until this month. On July 18, a suspected suicide bomber killed six people and wounded 30 aboard an Israeli tourist bus in a coastal town in Bulgaria. Israel quickly accused Hezbollah and Iran, longtime sponsor of the Lebanese Shiite militant group. Many questions remain about the bombing, and Bulgarian authorities have said they do not have proof implicating Hezbollah so far. Nonetheless, many Western counterterror officials share Israel's suspicions.

If the allegations are true, Iran and Hezbollah have crossed a dangerous line with their first strike in Europe in more than 15 years. The repercussions are stoking more turmoil in a Middle East torn by civil war in Syria and conflict over Iran's nuclear ambitions.

ProPublica has reviewed a string of plots attributed to the Shiite alliance, 10 cases in the past year alone, and found a complex and contradictory evolution of the threat. Iran and Hezbollah have waged a determined campaign to strike their enemies in retaliation for attacks on the Iranian nuclear program and the killing of a Hezbollah chief, counterterror officials say. The offensive led by the Quds Force, Iran's elite foreign operations unit, has displayed impressive reach and devastating potential.

"The Hezbollah-Quds force threat is the big thing worldwide right now," a U.S. counterterror official said. "There has been a wave of activity." 

Yet the modus operandi so far has veered between agility and clumsiness, precision and improvisation. Most of the attempted strikes have failed, often hampered by hasty execution and unreliable operatives, according to counterterror officials and experts around the world. In some ways the apparent opportunism and erratic behavior make the menace worse, increasing the chances of conflict with the West, experts say.

"These cases all seem amateurish," an Indian counterterror official said. "The Iranians feel great frustration and desperation because of the attacks on the nuclear program, a real desire to strike. So they aren't prepared -- they act quickly. They don't care about reprisals. They are out of practice. They have done few operations like this since the '90s."