WASHINGTON President Barack Obama's pick to become the top U.S. military officer warned Iran not to underestimate U.S. resolve in responding to attacks on U.S. forces in Iraq by Iranian-backed militia.
General Martin Dempsey did not outline potential U.S. responses in the Senate hearing on his nomination to become chairman of the U.S. military's Joint Chiefs of Staff, a post he is expected to assume in October.
But his remarks underscored growing U.S. concern in the wake of the killing of 14 U.S. service members in hostile incidents in June, the highest monthly toll in three years.
Asked what his message to Iran would be, Dempsey said: "It would be a gross miscalculation to believe that we will simply allow that to occur without taking serious consideration or reacting to it."
Dempsey appeared to signal his fear that Tehran might go too far, both in its actions in Iraq and with its nuclear program, which the West believes is aimed at making nuclear weapons. Tehran says the program is for peaceful purposes.
In his written response to questions from the Armed Services Committee, Dempsey wrote: "With its nuclear activities and its surrogate activities in southern Iraq, there is a high potential that Iran will make a serious miscalculation of U.S. resolve."
U.S. forces officially ended combat operations in Iraq last August but have come under increasing fire in recent weeks. Pentagon officials blame Shi'ite militias armed by Iraq's Shi'ite neighbour Iran for most of the recent attacks.
New Defense Secretary Leon Panetta this month urged Iraq to go after the Shi'ite groups responsible, and warned during his visit to Baghdad that the United States would take unilateral action when needed go after those threats.
Aides stressed at the time Panetta was referring to the right of U.S. forces to defend themselves on Iraqi soil.
Dempsey, who has commanded troops in Iraq, said Iran hoped to re-create a "Beirut-like moment" in Iraq, referring to the 1984 pullout from Lebanon's capital in the wake of attacks including a major suicide bombing targeting U.S. Marines.
"Iran's activities in southern Iraq are intended to produce some kind of Beirut-like moment ... and then in so doing to send a message that they have expelled us from Iraq," Dempsey said, citing the opinion of U.S. military leaders in Iraq.
The United States is on track to withdraw all of its 46,000 remaining forces from Iraq by the end of the year under the terms of a bilateral security pact.
Dempsey said he would favour keeping some U.S. forces in the country should Baghdad ask, but so far Shi'ite Prime Minister Nuri al-Maliki's coalition government has yet to make a decision whether it wants an extended troop presence or not.
"As long as we've got those soldiers there, we're going to do whatever we have to do to protect them. And I want to make sure that's clear to everyone," Dempsey told the committee.