WASHINGTON (AP) - The nation's U.S. intelligence officials said Thursday that if Iran is attacked over its alleged nuclear weapons program, it could retaliate by closing the Strait of Hormuz to ships and launch missiles at regional U.S. forces and allies. Testifying before the Senate Armed Services Committee, Defense Intelligence Agency chief Lt. Gen. Ronald Burgess said Iran is unlikely to initiate or intentionally provoke a conflict. His comments came amid growing international fears that Israel would launch military strikes against Iran to thwart its nuclear ambitions and counter recent diplomatic attacks in Thailand, India and Georgia. Israel has accused Iran of trying to kill its diplomats. Burgess and Director of National Intelligence James Clapper said they do not believe that Israel has decided to strike Iran. On the other side of the Capitol, Defense Secretary Leon Panetta said intelligence shows that Iran is continuing to enrich uranium but that Tehran has not made a decision to proceed with developing a nuclear weapon. The former CIA director said the United States is open to negotiations with Iran to find a diplomatic solution, but he said the U.S. keeps all options on the table to ensure that Tehran does not acquire a nuclear weapon. Clapper said it's "technically feasible" that Tehran could produce a nuclear weapon in one or two years, if its leaders decide to build one, "but practically not likely." Their testimony came as many in Congress are pressing the Obama administration to take tough steps against Iran, questioning whether diplomatic and economic sanctions have taken a toll on the regime. This issue of Iran has united Republicans and Democrats, who have clamored for harsh penalties. Last year, the Senate voted 100-0 to impose penalties on Iran's Central Bank, and President Barack Obama signed the sweeping defense bill containing the sanctions on Dec. 31. Speaking with reporters, House Speaker John Boehner, R-Ohio, said that for the sake of Israel and moderate Arab nations, "We need to take further action." "We gave the president a lot of tools to use," he said, referring to the Iran Sanctions Act. He's used some of them, but there are more tools available to the president to try to bring Iran into the world community. Boehner said it is "totally unacceptable" for Iran to develop nuclear weapons and said he agrees with Obama that "we should take no options off the table." "There has to be some resolution to this issue," Boehner told reporters. This issue is escalating. That causes me great concern. Associated Press writers Kimberly Dozier and Alan Fram contributed to this report.