Washington (CNN)As world powers rush to reach a framework deal curbing Iran's nuclear program ahead of a deadline Tuesday, a top official at a nuclear watchdog agency warned Tehran that it would not succeed in testing a nuclear weapon in secret, should it attempt to do so.
Watchdog group: We could detect an Iranian nuclear test
"If any country that would try today to hide a nuclear test explosion, we have, I would say, more than a 90% chance in detecting it," Lassina Zerbo, who runs the international agency that monitors global nuclear testing, told CNN in an exclusive interview.
The Comprehensive Nuclear Test-Ban Treaty (CTBT) organization has a worldwide network of sensors to identify signs of nuclear testing in the atmosphere, underwater and deep underground. Zerbo noted that "national technical means" in the United States, such as satellites and aircraft, are also used to detect nuclear tests by monitoring the release of radioactive material into the atmosphere. But he pointed out that the global network of sensors run by the CTBT, which has been adopted by the U.N., puts an international stamp on any finding.
"We've developed a system in a way that our detection capability ... can detect low-yield material, a low-yield explosion, better than what was anticipated when the treaty was negotiated," Zerbo said.
The talks underway in Lausanne, Switzerland, are aimed at keeping Iran from obtaining a nuclear weapon, but Zerbo offered assurance that even if the negotiations break down or Iran violates an agreement, the international community has ways of ascertaining its nuclear activities.
But despite Zerbo's confidence that his agency would find out about any test if Tehran were to conduct one, history has shown the challenges to this assertion. It took 55 days for sensors to pick up radioactive gases that had seeped into the atmosphere after North Korea set off a nuclear device in a sealed tunnel deep underground -- a delay that also complicated U.S. efforts to determine exactly what type of test North Korea had conducted.
"What we need is cracks in the ground that could let the gas seep through and be detected," Zerbo acknowledged.
Still, North Korea is one of only three countries that haven't adhered to the moratorium on tests called for under the treaty. Pyongyang conducted three -- in 2006, 2009 and 2013 -- and India and Pakistan in 1998. Between 1945 and 1996, when the CTBT first began gathering signatories, over 2,000 nuclear tests were carried on around the world.
Though Iran's leaders have denied that it wants an atomic bomb, its nuclear program currently puts in on the path toward acquiring such a weapon.
There have been dire predictions about what would happen if the U.S. and other world powers negotiating with Iran don't reach an agreement.
"Iran will immediately begin once again pursuing its nuclear program, accelerate its nuclear program, without us having any insight into what they're doing," President Obama said earlier this month.
The conventional wisdom has been if there is no permanent agreement to halt Iran's program, then Iranian enrichment facilities could begin making weapons-grade fuel. And that would open the door down the road to the test of a nuclear weapons device.
So Zerbo thinks it's urgent that Iran ratify the international test-ban treaty.
"First everyone talks about enrichment," Zerbo said, referring to negotiators' efforts to limit Iran's ability to enrich uranium to the levels used in a nuclear bomb. "But before we discuss this enrichment, let's get this treaty into force so that we don't even think about the process towards developing nuclear weapons."
And even with a deal, Iran will have plenty of its potential nuclear capability intact. It recently put a satellite in orbit using an intercontinental missile that could carry a warhead, leaving airstrikes as an option of last resort if there is no deal on its nuclear program.