Iran says a scientist killed in Tehran over the weekend was not connected with the country’s nuclear program, but the daylight killing and recent announcements by Tehran of nuclear advances have renewed scrutiny of the country’s nuclear effort.

Iranian media said 35-year-old Darioush Rezai-Nejad was a promising graduate student. Officials speculated that his assailants — gunmen on motorbikes — may have confused him with a nuclear scientist with a similar name.

Parliament Speaker Ali Larijani condemned the killing as a “U.S.-Zionist terrorist act.” Similar condemnations followed attacks on a number of Iranian scientists in recent years.

Attention On Nuclear Program

The latest killing follows Tehran’s announcement that it is installing a new generation of centrifuges to enhance its uranium enrichment program.

Mark Fitzpatrick, an analyst with the International Institute for Strategic Studies in London, says that if Iran’s claim is true, the number of more efficient, second-generation centrifuges may have increased from 20 to 164.

Fitzpatrick says that while that’s a cause for concern, it’s also a sign of how hard it is for Iran to replace thousands of older centrifuges.

“They have limitations on the amount of carbon fiber that they can import or produce, and there may be limitations in other components that restrict their capability to have many more than 164 [centrifuges],” he says.

Iran’s insistence that its program is entirely peaceful is widely doubted, Fitzpatrick says. But this year, Arab uprisings and international economic crises have dominated world leaders’ attention. That has left sanctions as the primary tool for dealing with Iran, Fitzpatrick says, though additional U.N. sanctions are unlikely in the near term.

Regional Focus On Arab Spring

“Meanwhile, the United States, through the Treasury Department, is employing a lot of pressure on banks and other financial institutions around the world to just stop doing business with Iranian organizations like the Iranian Revolutionary Guard Corps and its front companies that are caught up in the nuclear and missile trade,” Fitzpatrick says. “And it’s been a successful strategy, to persuade one company after another quietly to just stop doing business.[This] makes it harder for Iran to get the wherewithal to rapidly expand its programs.”

Within Iran, the president is in a very public feud with the country’s supreme leader, and economic reforms have caused sharp pain among ordinary Iranians.

Geneva-based nuclear analyst Shahram Chubin says amid such strife, the nuclear program represents a point of national pride that crosses much of the political spectrum. Chubin uses the word “inertia” to describe the steady progress of Iran’s nuclear program.

“While the sanctions are hurting, and while Iran has domestic political differences, and while the regional upheaval has not clearly been in Iran’s favor, there’s still a certain inertia behind the program, that makes it very difficult for them to stop or to reverse it,” Chubin says.

‘A Strong Bargaining Card’

Chubin says a recent Russian proposal is similar to previous confidence-building efforts in that it proposes a step-by-step program of increasing transparency on the part of Iran about its program in return for easing of sanctions. He doesn’t believe it will win favor in Tehran in the end.

“From the Iranian point of view, their belief is that the nuclear program gives them a strong bargaining card — that with the United States drawing down in Iraq and eventually in Afghanistan, Iran is in the position to negotiate with the West a much better outcome than it would without the nuclear program,” Chubin says.

Meanwhile, Iran has announced a plan to increase its stockpile of uranium enriched to 20 percent. Analysts say this is much closer to weapons-grade uranium than most of their stockpile, and will only increase Western concerns about whether Iran is laying the groundwork to pursue a nuclear weapon in the future.

Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.