With a portrait of the late Ayatollah Khomeini as a backdrop, Iran’s Islamic Revolutionary Guard Corps members display missiles during a parade marking the 31st anniversary of the start of the Iraq-Iran war, near Tehran on September 22, 2011. (AP Photo/Vahid Salemi, File)

(CNSNews.com) – A nine-year standoff between Iran and the West over Tehran’s nuclear programs may be entering a new and more serious phase, as the International Atomic Energy Agency (IAEA) prepares to release a report expected to raise the most significant concerns yet about Iranian nuclear activities.

According to diplomats, the report – to be released Tuesday -- will include suspicions that Iran has worked on computer models of a nuclear missile warhead, and point to the existence of a large steel container believed to be designed for nuclear weapons-related explosive testing.

Already the looming publication of the IAEA report has fueled speculation in Israel about the possibility of a military strike against Iranian nuclear facilities.

The U.S. House Foreign Relations Committee, with strong bipartisan support, last Wednesday advanced the toughest Iran sanctions legislation yet proposed.

Iran, which insists that its nuclear program has purely civilian applications, has already dismissed the claims reportedly contained in the IAEA report as “baseless and unauthentic.”

The fresh attention on the regime’s nuclear activities comes at a time of increased tension between Iran and the U.S., resulting from the exposure of an alleged plot by the Islamic Revolutionary Guard Corps’ foreign operations wing, the Qods Force, to carry out terror attacks on U.S. soil, beginning with the assassination of the Saudi ambassador in Washington.

After angrily denying the allegations, Iran stoked up the rhetoric on Friday with a display of anti-American bluster at an event marking the anniversary of the 1979 seizure of the U.S. Embassy in Tehran.

Addressing a large rally, Saeed Jalili, head of the Supreme National Security Council, waved documents which he said were among a batch Tehran would be submitting to U.N. secretary-general Ban Ki-moon this week providing evidence of U.S. terrorist plots against Iran.

Accompanied by chants of “Death to the U.S.,” Jalili did not provide much detail of the accusations, but did refer to the assassination of Iranians on U.S. sanctions lists for nuclear activities; alleged U.S. links with terrorist groups; and claims that U.S. officials had sent saboteurs to carry out terror attacks in Iran and the region.

“These are damning documents, which prove beyond any doubt that the U.S. recruits and trains terrorists,” he said. “The documents show how the U.S. government has been directing and funding these terrorist rings to sabotage the economic foundations and infrastructures of Iran and other regional states.”

Jalili said Ban would be directed to make the documents available to all U.N. member-states, and that Iran intended to bring legal action against the U.S.

Last week, supreme leader Ayatollah Ali Khamenei first announced the existence of “a hundred” documents which he said would be used to “dishonor the U.S. and those who claim to be the advocates of human rights and campaign against terrorism among the world public opinion.”

Similar comments came over the weekend from Foreign Minister Ali Akbar Salehi and others. One senior lawmaker, Zohreh Elahian, said Sunday the documents refer to acts of sabotage authorized after the eruption of protests following President Mahmoud Ahmadinejad’s disputed re-election in mid-2009.

Another lawmaker, deputy chair of the parliamentary national security and foreign policy committee Hossein Ebrahimi, said the publication of the documentation would trigger the downfall of the U.S. government.

The Fars news agency said the material included original documents and “first-hand audio and video files and pictures.”

‘Why don’t we kill them?’

Official Iranian outrage over purported U.S. threats has zoned in on a recent U.S. House Homeland Committee subcommittee hearing which heard experts call for strong, covert action against Iran.

During the Oct. 26 hearing on “Iranian Terror Operations on American Soil,” Gen. Jack Keane (ret.), a former U.S. Army vice chief of staff, questioned the effectiveness of sanctions, suggesting instead options including directed cyberattacks, covert actions, and assassination.

“Why are we permitting the Qods Force leaders, who have been organizing this killing of us for 30 years, to go around, still walking around?” he asked. “Why don’t we kill them? We kill other people who are running terrorist organizations against the United States. These guys have killed almost a thousand of us. Why don’t we kill them?”

Also testifying before the panel, Foundation for Defense of Democracies senior fellow Reuel Marc Gerecht, a former CIA operative, argued that the Iranian regime was not fazed by economic sanctions, and suggested that the head of the Qods Force be targeted.

“Iran would not look like the country it is today if they were concerned about the bottom line,” Gerecht said. “So I don’t think that you’re going to really intimidate these people, get their attention, unless you shoot somebody – it’s pretty blunt, but I don’t think you get to get around it.”

If the IRGC’s Qods Force was held responsible for the assassination plot, he continued, then Qods Force commander Ghasem Soleimani should be held accountable.

“Ghasem Soleimani travels a lot, he’s all over the place,” Gerecht said. “Go get him. Either try to capture him, or kill him. I think you have to send a pretty powerful message to those who have undertaken this, or I think down the road you’re asking for it. They will read this not as a response of someone who’s strong, but as a response of someone who’s weak.”

(Soleimani is one of five Iranians designated by the U.S. Treasury Department last month under an executive order designed to disrupt funding to terrorists, following exposure of the alleged Qods Force assassination plot.

He had already been designated twice before under the order – once based on his relationship with the IRGC and once, last May, based on IRGC activities in support of Syrian President Bashar Assad’s violent crackdown on dissent.

The executive order freezes any assets Soleimani may have in the U.S. and prohibits American citizens from engaging in transactions with him.)

Iran’s Kayhan newspaper reports that the Iranian government summoned the Swiss ambassador – who handles matters relating to the U.S. in the absence of ties between Washington and Tehran – to protest the remarks made during the hearing.

Salehi, the foreign minister, on Sunday threatened legal action against the U.S. government in response to what he said were brazen calls for the assassination of Iranian officials.

Also unhappy about the remarks was Defense Minister Ahmad Vahidi, who linked the assassination remarks to what he called a “devilish triangle of terrorism, human rights violation and use of WMDs.”

Vahidi, himself a former head of the Qods Force, is wanted for international terrorism.