WASHINGTON—U.S. officials are increasingly concerned about what they call a growing terrorist threat from Iran as well as an emerging al Qaeda presence in Syria, according to an annual State Department report assessing terrorism trends in 2011.
In its first report since the killing of Osama bin Laden and a number of his top lieutenants last year, the State Department reported a shift in the threat facing the U.S., away from one largely driven by al Qaeda's core leadership in Pakistan and toward a more diffuse set of regional al Qaeda affiliates.
In what the report called "a landmark year in counterterrorism," it said the killing of bin Laden and several other key leaders last year "puts the network on a path of decline that will be difficult to reverse."
The expanded array of terrorist threats reflects the changing national-security landscape in the wake of the Arab Spring, growing fears about a conflict with Iran, and the blows to al Qaeda's leadership.
"We are increasingly concerned about Iran's support for terrorism and Hezbollah's activities," said Daniel Benjamin, the State Department's counterterrorism chief, adding that both appear to have stepped up their terrorist activity in the past year and "are engaging in their most active and aggressive campaign since the 1990s." The U.S. views Hezbollah of Lebanon as a proxy of Iran.
The U.S. has accused Iran's elite Quds Force of plotting to kill the Saudi ambassador in Washington—Iran denied the charge—and the U.S. and other countries have accused Iran of backing recent plots against Western and Israeli targets in Azerbaijan, Thailand, India and Kenya. Israel has accused Hezbollah of a recent attack on Israeli tourists in Bulgaria, though U.S. officials have only said the attack bore some hallmarks of Hezbollah.
Iran also has allowed al Qaeda members to move money and operatives through Iranian territory to South Asia, the report said. Iran has denied any connection with al Qaeda.
The White House, intensifying steps to pressure Iran over its disputed nuclear program, announced on Tuesday new executive orders to tighten sanctions, particularly on Iran's energy sector. The new sanctions are intended to make it harder for Iran to circumvent existing sanctions, targeting its petrochemical sector along with a pair of foreign banks that have been doing business with Tehran. Congress is also expected to pass this week a new suite of sanctions that would ramp up penalties on Iran's energy, financial and transportation sectors.
Obama administration officials said sanctions already in place have had a significant impact on the Iranian economy, leading to the loss of more than 1 million barrels a day of oil exports, or about $9 billion in revenue to Tehran each quarter. The new sanctions also call for penalties for anyone buying Iranian petrochemical products, which bring Tehran about $9 billion a year.
Further, the executive orders impose sanctions on the Bank of Kunlun, in China, and the Elaf Islamic Bank, in Iraq, for conducting business with Iranian banks designated by U.S. authorities for supporting Iran's terrorism and proliferation activities.
The annual terrorism report examined the revolutions in Arab countries over the past year and a half, saying some have created instability that could create opportunities for al Qaeda terrorists to gain momentum, as they did in Yemen.
The report notes that toward the end of 2011, al Qaeda's Iraq branch "was believed to be extending its reach into Syria and seeking to exploit the popular uprising" against the Assad regime.
Mr. Benjamin said that while the number of al Qaeda fighters in Syria is "relatively small," there is a larger group of foreign fighters either in or on their way to Syria. He added that the U.S. is concerned that extremist groups will infiltrate Syrian opposition groups, which have stated they don't want to align themselves with extremist elements.
There were 10,283 terrorist attacks in 70 countries that resulted in more than 12,500 deaths last year, the report said. That total reflected a 12% decline in attacks from 2010.
Activities by some specific groups have been on the rise, particularly in Africa, where the Nigerian-based terror group Boko Haram carried out 136 attacks in 2011, up from 31 a year earlier. Across Africa, terrorist attacks grew 11.5%, according to the report.
While the number of al Qaeda attacks grew 8%, much of that was attributable to the growth in attacks by al Qaeda's East African affiliate, al-Shabaab, which carried out 544 attacks in 2011.—Keith Johnson contributed to this article.
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A version of this article appeared August 1, 2012, on page A8 in the U.S. edition of The Wall Street Journal, with the headline: U.S. Sees Shift in Threat From Iran and al Qaeda.