A tit-for-tat war seems to have begun between the US and Tehran over the Islamic Republic's alleged nuclear file. Rasha Saad reports United States officials said on Tuesday that two Iranian security guards at the diplomatic mission of Iran at the United Nations have been expelled from the US. The Iranians were expelled after the mission was repeatedly warned against its guards videotaping bridges, the Statue of Liberty and the New York subway. According to officials, it was the third time Iranian guards at the mission had been involved in such activity, following similar incidents in June 2002 and November 2003. "We were very concerned because these activities are incompatible with the stated purpose of their duties," said Richard Grenell, spokesman for the US mission to the United Nations. In Tehran, a Foreign Ministry official said, "such behaviour runs against international conventions and lacks political judgement and moral value." Filming in public places violates no US law but US officials disclosed in May 2003 that they intended to question two Iranian security guards who had been seen photographing bridges and the Statue of Liberty in the New York harbour, which they said could be targets for terrorist attacks like those that took place on 11 September 2001. Coming only days after the US, the European Union and the International Atomic Energy Agency (IAEA) condemned Iran on Saturday for resuming centrifuge parts production, the US move was believed to be a message for Tehran. "The US wants to deliver a message to Tehran that it will continue to pressure it over its nuclear file," Iranian analyst Mohamed Sadeq Al-Husseini told Al-Ahram Weekly. He added that Washington refuses to deal with Iran as a sovereign state with a political will of its own. "The problem with Washington is that it seeks to bring Iran on its knees over its nuclear activities rather than establishing dialogue on the issue, as the Europeans do," he added. On Sunday, the US condemned Iran for persisting with what Washington regards as a nuclear bomb- making programme. "Iran needs to come clean and fully cooperate with its international obligations," White House spokesman Scott McClellan said. The expulsion of the two guards was not the only message of its kind. Iran's government complained on Monday that one of its diplomats in Iraq had been briefly detained and questioned by US forces, accusing American troops of failing to respect his diplomatic status. The diplomat was then reportedly released. Iran said on Sunday it would resume building centrifuge parts for its nuclear programme on Tuesday, shrugging off international condemnation and US alleged fears that it is hiding a secret nuclear project. While nuclear fuel cycle work is permitted under the Nuclear Non-Proliferation Treaty (NPT), Iran was forced to agree to a package that entailed so-called "confidence-building" measures -- suspending enrichment work and allowing tough inspections -- pending the completion of the 15- month-old probe. Iran's decision to resume the manufacture of centrifuges was thus in retaliation for an IAEA resolution last week that "deplored" Iran's failure to cooperate fully with IAEA inspectors. Expressing bitterness over what Iran perceived as an "unfair" resolution and over a broken promise from Britain, France and Germany to close Iran's dossier at the IAEA's board meeting last week, the Islamic Republic sent a letter to the agency informing it that it "intends to resume, under IAEA supervision, manufacturing centrifuge components and the assembly and testing of centrifuges as of 29 June". "They may react bitterly or heighten pressure on us, but that is not important," the secretary-general of Iran's Supreme National Security Council and man responsible for Iran's nuclear file, Hassan Rohani, told parliament on Sunday. "It is Iran's natural right to resume assembling and making centrifuges," Iranian Foreign Minister Kamal Kharrazi said. But Iran tempered its defiant stance with a pledge to continue to allow UN inspectors access to nuclear sites for snap inspections and an assurance that it had no immediate plans to resume uranium enrichment but only intended to return to the manufacture of centrifuges. Centrifuges are devices that purify uranium gas by spinning at supersonic speeds. The enriched uranium produced can be used in nuclear power plants or in the manufacture of nuclear weapons. "Making centrifuges is different from enriching uranium," Kharrazi said. Iran insists its nuclear programme is peaceful. While Washington pushed its Western allies to take a tougher line on Iran during last week's IAEA meeting in Vienna, the agency itself resisted, preferring to continue efforts to persuade Tehran that it is in its interests to come clean on nuclear activities. So far, the IAEA's policy seems to have paid off. The IAEA's head, Mohamed El-Baradie, praised Iran for allowing inspectors prompt access on Monday to Lavizan -- the site where Washington suspects Iran carried out secret nuclear weapons- related activity. Lavizan, situated near a military installation in the Iranian capital, was recently destroyed. El-Baradie said Tuesday that Iran told UN nuclear inspectors that Lavizan was used for military research before it was razed and not, as Washington suspects, for atomic activity. El-Baradie, however, said that the IAEA still wants Iran to do more to convince the world that its nuclear projects were peaceful. During his visit to Russia late this week, El- Baradie also said he was unconcerned by Russia's construction of a nuclear reactor in Iran, brushing aside US allegations that the facility could be used to develop nuclear weapons. Washington has strongly criticised Russia for pushing ahead with the construction of the $800 million reactor near the Iranian port of Bushehr, saying Tehran could use Moscow's atomic know-how to develop nuclear weapons of its own. "Bushehr is not apparently at the centre of international concern because Bushehr is a project to produce nuclear energy," El-Baradie said after talks with Russian President Vladimir Putin. A Moscow source involved in the Bushehr project said on condition of anonymity that El-Baradie's support was crucial at a time when Washington seemed to be stepping up criticism of Iran's nuclear programme. "He publicly threw his weight behind Russia, and that's really important for us to keep the project rolling," the source said. To allay US concerns that Iran could extract plutonium from Bushehr's spent nuclear fuel and make bombs, Russia has pledged to sign a deal with Iran to oblige it to return all fuel to Russia after a decade of use at Bushehr. El-Baradie said the fuel "could be a concern" but praised Russia's resolve to get it back.