VIENNA -- Russia said Wednesday the world should not draw "hasty conclusions" over Iran's most recent rebuff of U.N. attempts to investigate allegations the Islamic Republic hid secret work on atomic arms, but the U.S. and its allies accused Tehran of nuclear defiance.
Under international pressure to show restraint, Israel, which has warned repeatedly that it may strike Iran's nuclear facilities, pointedly urged major world powers to mind their own business, saying it alone would decide what to do to protect the Jewish state's security.
France said Iran's continued stonewalling of the International Atomic Energy Agency "is contrary to the intentions" expressed by Tehran in its recent offer to restart talks over its nuclear activities.
In Washington, White House spokesman Jay Carney said while world powers have not yet reached a decision on those talks, Iran's refusal to cooperate with the investigation "suggests that they have not changed their behavior when it comes to abiding by their international obligations."
The IAEA's acknowledgment of renewed failure came early Wednesday at the conclusion of the second trip in less then a month aimed at investigating suspicions of covert Iranian nuclear weapons work.
The IAEA team had hoped to speak with key Iranian scientists suspected of working on the alleged weapons program, break down opposition to their plans to inspect documents related to nuclear work and secure commitments from Iranian authorities to allow future visits.
But mission head Herman Nackaerts acknowledged his team "could not find a way forward" in negotiations with Iranian officials. A separate IAEA communique clearly -- if indirectly -- blamed Tehran for the lack of progress.
"We engaged in a constructive spirit, but no agreement was reached," it quoted IAEA chief Yukiya Amano as saying.
Iran continued sounding a hard line, with supreme leader Ayatollah Ali Khamenei telling the nation's nuclear scientists to forge ahead with the atomic program.
"Sanctions and political pressures won't have any effect. When a nation decides to resist, when it believes in its domestic power and its own capability, nothing can stop it," Khamenei told the scientists, adding: "I pray for you."
As on the previous visit that ended in early February, Iran did not grant requests by the IAEA mission to visit Parchin -- a military site thought to be used for explosives testing related to nuclear detonations, the statement said
The statement also said that no agreement was reached on how to begin "clarification of unresolved issues in connection with Iran's nuclear program, particularly those relating to possible military dimensions."
The Washington-based Institute for Science and International Security said Wednesday it had new indications of hidden weapons work by Iran.
ISIS said that a cache of telexes to Western high-tech companies from the Physics Research Center in Tehran shows that from about 1990 to 1993, the center sought to purchase equipment and materials that could have been used in weapons research and development.
Tehran has acknowledged that the Physics Research Center in Tehran conducted nuclear-related research, but said the center's work was limited to efforts to prepare Iran's military and civilian population for dealing with a nuclear strike.
Iran insists it is using nuclear energy only to generate power, and Khamenei proclaimed Wednesday that possession of atomic arms is a sin as well as "useless, harmful and dangerous." Iran asserts that the allegations of secret work on developing nuclear arms are based on fabricated U.S. and Israeli intelligence.
But in a 13-page summary late last year, the IAEA listed clandestine activities that he said can either be used in civilian or military nuclear programs, or "are specific to nuclear weapons."
Among these were indications that Iran has conducted high-explosives testing to set off a nuclear charge at Parchin.
Other suspicions include computer modeling of a core of a nuclear warhead and alleged preparatory work for a nuclear weapons test and development of a nuclear payload for Iran's Shahab 3 intermediate range missile -- a weapon that could reach Israel.
The IAEA trip and its aftermath was accompanied by renewed saber-rattling by Iran and Israel.
Iranian Gen. Mohammed Hejazi, who heads the military's logistical wing, warned that Iran will "not wait for enemies to take action against us."
"We will use all our means to protect our national interests," he told the semiofficial Fars news agency.
His comments followed Iran's announcement of war games to practice protecting nuclear and other sensitive sites, the latest military maneuver viewed as a message to the U.S. and Israel that the Islamic Republic is ready both to defend itself and to retaliate against an armed strike.
Israel and the U.S. have said military force remains a last-ditch option to stop Iran from developing a nuclear weapon, but while Washington has recently tamped down its rhetoric -- and is thought to be urging Israel to practice restraint -- the Jewish state remains bellicose.
Russia, too, warned Israel against the consequences of attacking Iran, with Deputy Foreign Minister Gennyadi Gatilov telling the ITAR-Tass news agency Wednesday that such a strike "would be a catastrophe not only for the region but for the whole system of international relations."
But Israeli Foreign Minister Avigdor Lieberman rebuffed both Washington and Moscow, telling Israel's Channel 3 TV news the issue "is not their business."
"The security of the citizens of Israel, the future of the state of Israel, this is the responsibility of the Israeli government," he said. "We will make the best decision for the Israeli interest."
Shannon Kile, head of the Nuclear Weapons Project at the Stockholm International Peace Research Institute, warned the risk of military conflict was rising -- and not necessarily through the threat of direct Israeli attack.
"There is an escalation dynamic under way, especially in the Persian Gulf, where you could have a conflict arising from an accident, a misunderstanding, from a local commander acting on his own initiative and I think that's the problem," Kile said.
In Paris, Foreign Ministry spokesman Romain Nadal said Tehran's continued stonewalling of the probe, now in its fourth year, "is another missed opportunity for Iran" to ease suspicions about its nuclear goals and reconcile with the rest of the world. Nadal said Iran's refusal to cooperate on the issue "is contrary to the intentions" of Iran's recent offer to restart nuclear talks after a series of abortive meetings over the past two years.
German Foreign Minister Guido Westerwelle said Iran's intransigence "is the path the leads to further international isolation." But German officials were cautious when asked about the possibility of imposing yet more sanctions against Iran in response to the latest setback.
Britain, which would join the U.S., China, Russia, France and Germany in any nuclear negotiations with Iran, said it wasn't yet clear what impact the IAEA visit's failure might have on the international community's response to Tehran's recent offer of renewed talks.
"We share the IAEA's disappointment. The IAEA genuinely wants to make progress and we want the Iranians to engage in meaningful talks," a spokesman for Britain's foreign ministry said on customary condition of anonymity in line with policy.
Russia urged renewed efforts to engage Iran on its suspected secret nuclear work.
"We must not make hasty conclusions," Gatilov, Russia's deputy foreign minister, told reporters, calling for the IAEA to "continue contacts" with Iran on the issue.
The IAEA said no further talks were planned for the moment. But Iran's envoy to the IAEA, Ali Asghar Soltanieh also said "more time was needed" for final agreement on the issue.