Reporter: U.S. planning Iran bombs CAIRO, Egypt (CNN) -- The Pentagon is engaged in intensive planning to carry out a bombing campaign in Iran on a day's notice to halt the flow of Iranian aid to sectarian militants in Iraq, Pulitzer-Prize winning journalist Seymour Hersh said Sunday. A bombing campaign could be ready to launch as soon as this spring, Hersh wrote in an article published Sunday in "The New Yorker." Previously, he said, the Bush administration had been focused on plans to destroy Iran's nuclear facilities and possible regime change. The Pentagon on Friday said in a written statement that "The United States is not planning to go to war with Iran. To suggest anything to the contrary is simply wrong, misleading and mischievous. "The United States has been very clear with respect to its concerns regarding specific Iranian government activities," the statement continued. "The president has repeatedly stated publicly that this country is going to work with allies in the region to address those concerns through diplomatic efforts." And Defense Secretary Robert Gates said on February 15: "We are not, you know, for the umpteenth time, we are not looking for an excuse to go to war with Iran. We are not planning a war with Iran." In the article, Hersh reported that a former senior intelligence official told him that the Pentagon's top brass "were counting on the White House's not being foolish enough to do this in the face of Iraq and the problems it would give the Republicans in 2008." In an interview on CNN's "Late Edition with Wolf Blitzer," Hersh said U.S. military plans are "very far along" and that U.S. special operations and intelligence forces have been crossing into Iran "for months." "There has been a lot of jumping over the border, chasing bad guys, or people we think are bad guys," he said in an interview from the Egyptian capital Cairo. But the U.S. military has been stretched thin by the war in Iraq, which will enter its fifth year next month. And Hersh told CNN the Navy is concerned that, in the event of a U.S. attack, an aircraft carrier in the Strait of Hormuz off Iran's southern coast could be vulnerable to attack by any of Iran's hundreds of patrol boats. Hersh said he has seen "a lot of evidence" that, in anticipation of a possible attack, Iranians "are digging more holes, moving their leadership into underground bunkers in other places besides Tehran in case of a bombing. They are anticipating the worst." Rep. Duncan Hunter, R-Calif., did not appear alarmed by Hersh's reporting. "We have contingency plans around the world," Hunter, a presidential hopeful and the former chairman of the House Armed Services Committee, told CNN. "We had contingency plans with the Soviet Union, and we had specific targets. That didn't mean we were planning to attack the Soviet Union." But Hersh pointed to Vice President Dick Cheney's comments last week in Australia, where he said "all options are on the table" regarding Iran. Though such talk may amount to nothing more than "agitprop, propaganda," Hersh said, "Inside the military, they are planning very seriously, at the president's request, to attack Iran." Hersh, who has covered the issue for years, said movement toward an incursion appears to be ratcheting up. He predicted that Bush, whose second term ends in January 2009, "is not going to leave office without doing something about Iran." He criticized the president for refusing to negotiate with Iranian officials unless they agree first to suspend the country's nuclear program. U.S. officials accuse Iran of attempting to join the elite club of countries that have nuclear weapons; Iran insists its nuclear program is intended solely for peaceful purposes. Meanwhile, Hersh said the Bush administration has been pumping "a great deal of money" -- some of it from Saudi Arabia, and all of it without congressional oversight -- to fund covert operations in the Middle East to stop the spread of Shiite influence in the so-called Shiite Crescent, which includes Lebanon. Citing government consultants, Hersh wrote that Cheney was guiding the clandestine side of the effort. His article said that no one from his office or the administration would comment. Hersh said the administration has decided to pressure Shiites -- whether they be Iranians or Hezbollah, whose leader, Hassan Nasrallah, has described the situation as a civil war. "As far as he is concerned, we are interested in recreating what is happening in Iraq in Lebanon, that is Sunni versus Shia," Hersh said. Some of the money, he said, has made its way to three Sunni jihadist groups in Lebanon that are connected to al Qaeda and opposed to Hezbollah, the Shiite militia that sparked a month-long war with Israel last summer. Hersh said his sources told him that much of the money used to fund the effort has come from Iraq, "where there is all kinds of piles of loose money, pools of cash that could be used for covert operations." He called for a congressional investigation of those allegations. "We are simply in a situation where this president is really taking his notion of executive privilege to the absolute limit here, running covert operations, using money that was not authorized by Congress, supporting groups indirectly that are involved with the same people that did 9/11, and we should be arresting these people rather than looking the other way," he said. Hunter, now the ranking Republican on the Armed Services Committee, noted that Iran has not suspended its nuclear program. Under those circumstances, "that military option is on the table. At some point, it may have to be exercised." However, Rep. Jane Harman, who leads the intelligence subcommittee of the House Homeland Security Committee, said she was not impressed with the intelligence on Iran's nuclear program. She called it "quite inconclusive," and warned against making any military moves based on that information. "Let's not make the mistake in Iran that we did in Iraq," Harman added, in a reference to the non-existent weapons of mass destruction that once served as Bush's justification for invading Iraq. The California Democrat said economic sanctions against Iran appear to be succeeding in persuading it to scale back its nuclear ambitions, and Congress would need to approve any military action. "I think we have a real shot at changing the policy in Iran in a way that would be very constructive and much more effective than this notion of military action," she said.