Iran defiant, but is it just a show?

TEHRAN, Iran - Iran claimed Wednesday that it has achieved two major advances in its program to master production of nuclear fuel, a defiant move in response to increasingly tough Western sanctions over its controversial nuclear program.

It may have come as a surprise to some when Iranian President Mahmoud Ahmadinejad went on TV to brag about their nuclear achievements. However, while Iran's president may have impressed his own people by showcasing his country's latest advances in nuclear technology, CBS News correspondent David Martin reports that experts like David Albright, founder of the non-governmental Institute for Science and International Security, found no new evidence Iran is dramatically closer to building a bomb.

"The announcement today certainly is an attempt to show Iranian resolve in the face of international opposition, but they say that every day, and this doesn't really add any credibility to that threat," Albright says.

Both the fuel rods loaded into a research reactor and the new centrifuges for enriching uranium had already been seen by U.N. inspectors and so came as no surprise to U.S. intelligence.

"But it does show continuing progress that's building toward a capability that if Iran made a decision to build nuclear weapons it could implement fairly quickly," Albright says.

In a further show of resistance to international pressure, Foreign Ministry spokesman Hasan Tajik said six European diplomats were summoned Wednesday and told that Iran has no problem replacing customers - an implied threat that Tehran would carry out plans to cut European Union countries off immediately to preempt sanctions set to go into effect in July.

Tajik's comments reversed earlier reports that Tehran already was taking steps to halt sales to six countries.

Iranian TV reported that crude oil exports to six European nations - Italy, Spain, Portugal, Greece, France and the Netherlands - were cut earlier in the day. A semi-official news agency later reported that exports were cut just to France and Netherlands with the four other countries receiving an ultimatum.

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The EU ban on oil imports is to go into effect in July. Iranian officials say their country's earlier cutoff will hit European nations before they can line up new suppliers, and that Tehran has already lined up buyers for the 18 percent share of its oil that goes to Europe.

Iran's tough tone comes as tensions have mounted dramatically with Israel and the United States over its nuclear program, which Washington and its allies say is aimed at producing a nuclear weapon. Iran denies the charge, saying its program is intended solely for research and generating electricity. Israel has increasingly warned of the possibility of a military strike on Iran's nuclear facilities, and it has accused Iran of being behind attempted attacks on Israeli diplomats in India, Georgia and elsewhere. Iran denies any role in the attacks, which have resembled recent bombing-assassinations of Iranian nuclear scientists that Tehran has blamed on Israel.

Iran's top nuclear negotiator on Wednesday formally notified the European Union's foreign policy chief that Tehran is willing to return to talks with the world powers on its nuclear program. Many in the West however feel that negotiations are a ploy to buy time.

"Iran has still not granted the International Atomic Energy Agency the access that they want," said CBS News foreign affairs analyst Pamela Falk, "and the nuclear announcement by the government does not reassure the inspectors."

Iran is meanwhile pushing ahead on what it says is a drive toward nuclear-self-sufficiency.

On Wednesday, President Mahmoud Ahmadinejad oversaw the insertion of the first Iranian domestically made fuel rod into a research reactor in northern Tehran, the country's official IRNA news agency reported.

Separately, the semiofficial Fars agency reported that a "new generation of Iranian centrifuges" had been installed and had gone into operation at the country's main uranium enrichment facility at Natanz in central Iran.

The moves were aimed at showing that Iran is mastering the entire cycle of producing nuclear fuel on its own. In the fuel cycle, mined uranium is processed into gas, then that gas is spun in centrifuges to purify it. Low-enriched uranium -- at around 3.5 percent -- is used to produce fuel rods that power a reactor; however, the same process can be used to produce highly enriched uranium -- at around 90 percent purity -- that can be used to build a warhead.

Western experts Wednesday morning cast doubt on Iran's claims that its centrifuges have reached the fourth-generation capabilities, saying that the Iranians have been struggling to reach second- or third-generation centrifuges. But Iran has exaggerated its nuclear capabilities before.

"It's probably a lot of hyperbole," Mark Fitzpatrick, a non-proliferation expert at the International Institute of Strategic Studies, told CBS News. He has not heard of a fourth-generation centrifuge in Iran and doubts one even exists there.

CBS News national security analyst Juan Zarate said that Iran has good reason for issuing continuous announcements on its nuclear program in the face of pressure from the international community.

The Tehran facility where IRNA said the new fuel rods were installed is a research reactor intended to produce medical isotopes used in the treatment of cancer patients. It requires fuel enriched to around 20 percent, considered a threshold between low and high enriched uranium.

Iran has been producing uranium enriched up to 5 percent for years, and began enriching up to near 20 percent in February 2010 after attempts at a deal with the West to import the fuel rods broke down. In January, Iran said it had produced its first such fuel rod. IRNA said the nuclear fuel rods were produced at a plant in Isfahan, central Iran.

Fitzpatrick said Iran's production of 20 percent uranium certainly "gets it closer" to being able to produce weapons grade uranium but that they are by no means near this objective.

Iranian officials have long spoken of introducing faster, more efficient centrifuges at the Natanz facility. The Fars news agency report did not give details on the advanced models that were installed.

Iran's Oil Minister Rostam Qassemi said several days earlier that Tehran could cut off oil exports to "hostile" European nations.

Members of Iran's parliament have been discussing a draft bill, although not finalized, which would cut off the flow to the European Union before the latest EU sanctions on Iran go into effect this summer.

Apart from the EU's recent measures on Iran, which include an oil embargo and a freeze of the country's central bank assets, Washington also recently levied new penalties aimed at limiting Iran's ability to sell oil -- which accounts for 80 percent of its foreign revenue.

Iran's unchecked pursuit of the nuclear program scuttled negotiations a year ago, but Iranian officials last month proposed a return to the talks with the five permanent U.N. Security Council members plus Germany.

IRNA news agency on Wednesday reported that Iran's top nuclear negotiator Saeed Jalili had written to the European Union's foreign policy chief Catherine Ashton, to formally announce its readiness to start those negotiations.

In the past, Iran has angered Western officials by appearing to buy time through opening talks and weighing proposals even while pressing ahead with the nuclear program.