Al Qaeda was interested in plotting attacks against America's oil and gas infrastructure as late as 2010, according to a bulletin issued by the Department of Homeland Security.
"DHS and FBI issued an intelligence note to its federal, state, local, tribal and private sector partners to provide greater insights into al-Qa'ida's interest in targeting oil and natural gas infrastructure. We are not aware of indications of any specific or imminent terrorist attack plotting against the oil and natural gas sector overseas or in the United States," DHS press secretary Matthew Chandler said in a statement, referring to the bulletin. "However, in 2010 there was continuing interest by members of al-Qa'ida's in targeting oil tankers and commercial oil infrastructure at sea. We have no information of any imminent terrorist threat to the maritime or energy sectors, but wanted to make our partners aware of the alleged interest; it is unclear if any further planning has been conducted since mid-last year."
The notice said that the government agencies did not issue a full alert because Chandler said alerts only come "when we have specific or credible information to convey to the American public."
The bulletin came out in response to evidence uncovered in the Navy SEAL raid that killed al Qaeda's leader, Osama bin Laden, on May 2, U.S. officials told ABC News. There was no specific time or date for a threatened attack, the official said. Analysts have been poring over the trove of personal documents and computer files kept by bin Laden and have already uncovered what one official called al Qaeda's "playbook." U.S. officials sifting through the cache of intelligence said they learned more in the first 10 days of analysis than in the last 10 years hunting al Qaeda.
Other potential plots uncovered included similar "interest" in targeting America's rail system and an aspiration to assassinate President Obama. Many of the proposed operations were detailed in what officials described as a "professional journal" kept by bin Laden.
Targeting tankers would not be a new tactic for al Qaeda. In 2002, the group claimed responsibility for the bombing of a French oil supertanker off the coast of Yemen.
ABC News' Lee Ferran contributed to this report.