VIENNA — Iran could produce enough weapons-grade uranium to arm a nuclear bomb within two to four months but would still face serious engineering challenges — and much longer delays — before it succeeds in making the other components needed for a functioning warhead, a respected US think tank said Monday.
In its report, the Institute for Science and International Security did not make a judgment on whether Iran plans to turn its enrichment capabilities toward weapons making.
While Iran denies any interest in possessing nuclear arms, the international community fears it may turn its peaceful uranium enrichment program toward weapons making — a concern that is growing as Tehran expands the number of machines it uses to enrich its stockpile of enriched uranium.
As those fears grow, so does concern that Israel could carry out its threats to attack Iran’s nuclear facilities before that nation reaches the bomb-making threshold.
In a strident call for an internationally drawn ‘‘red line’’ on what he said is Iran’s move toward nuclear arms, Prime Minister Benjamin Netanyahu of Israel said on Sept. 28 that the world has until next summer at the latest to stop Tehran before it can build an atomic bomb.
Showing a diagram of a cartoon-like bomb before the UN General Assembly, Netanyahu said Iran is ready to move to the final stage of making such a weapon by then.
For now, US military and intelligence officials say they don’t believe Iran’s leadership has made the decision to build a bomb, while also warning that the country is moving closer to the ability to do so.
In its report, the Institute for Science and International Security drew a clear distinction between making a warhead and Tehran’s ability to make the fissile core of a warhead by producing 55 pounds of weapons-grade uranium from its lower enriched stockpiles.
‘‘Despite work it may have done in the past,’’ Iran would need ‘‘many additional months to manufacture a nuclear device suitable for underground testing and even longer to make a reliable warhead for a ballistic missile,’’ the report said.