The United States fears the Iranian-backed Lebanese militant group Hezbollah may be planning imminent attacks in Europe and around the world, a senior security official in Washington said on Friday.
"Our assessment is that Hezbollah and Iran will both continue to maintain a heightened level of terrorist activity and operations in the near future," said Daniel Benjamin, the US State Department's counter-terrorism coordinator.
"We are increasingly concerned about Hezbollah's activities on a number of fronts, including its stepped up terrorist campaign around the world," he said.
"And we assess that Hezbollah could attack in Europe or elsewhere at any time with little or no warning," he warned, in a conference call with reporters to announce new US sanctions against Hezbollah, Iran and Syria.
Hezbollah is a Shiite armed faction that within Lebanon operates as a political party and as a "resistance" force to counter Israel, and which Western powers says runs an international militant network.
It is backed by Damascus and Tehran, and has been accused both of carrying out recent bomb attacks on Israeli targets in Europe and Asia and of backing Syrian strongman Bashar al-Assad's brutal crackdown on an armed revolt.
Benjamin warned Hezbollah might step up violent action as international economic sanctions turn the screw on its backers in Iran and Western-backed Syrian rebels threaten to overthrow its sponsor in Damascus.
"Hezbollah maintains a presence in Europe and its recent activities demonstrate that it is not constrained by concerns about collateral damage or political fallout that could result from conducting operations there," he said.
"Hezbollah believes there have been sustained Israeli and western campaigns against the group and its primary backers Iran and Syria over the past several years and this perception is unlikely to change," he continued.
"Both remain determined to exact revenge against Israel and to respond forcefully to the Western-led pressure against Iran and Syria," he said.
"This suggests more acts of terrorism by both Hezbollah and Iran are likely and they will continue to pose a serious threat for the foreseeable future.
"We have not detected any operational activity of the group in the United States," he added. "We do not have any information on any operational targeting or anything like that in the US.
"But, that said, it's a very ambitious group with global reach."