Attempts to derail a country's nuclear programme by killing its scientists "are products of desperation"

".... The Doomsday Clock – the famous gauge of the world's risk of nuclear annihilation, run by the Bulletin of the Atomic Scientists (BAS) – moved a minute closer to midnight on Tuesday. Then on Wednesday, another nuclear physicist was assassinated in Iran. Both events reveal a global nuclear situation that seems to be worsening fast.... 

He is the fifth such victim in Iran, according to William Tobey of the Belfer Center for Science and International Affairs at Harvard University. Two nuclear scientists were killed in similar bombings in 2010, an electronics student was shot dead last year, and another physicist is thought to have been killed in 2007. Another 2010 bombing target, Fereydoon Abbasi, survived and was made head of the Atomic Energy Organization of Iran. No one has claimed responsibility for any of the attacks.

Losing hope

In January 2010 things seemed more hopeful. US president Barack Obama's renewed commitment to nuclear disarmament led the BAS to set its clock back to 6 minutes to midnight, from the 5 it had moved to previously, as the US seemed to retreat from arms control. The clock started at 7 minutes to midnight in 1947, in the wake of the nuclear attacks on Hiroshima and Nagasaki in Japan.

This week security experts moved it to 5 minutes to midnight again, citing failure by the US and others to follow through on arms control promises – and also Iran's nuclear power programme. Iran's two uranium enrichment plants are busily making uranium that could be used to fuel a reactor that makes medical isotopes, but could also be used to quickly produce weapons-grade uranium, in which the uranium-235 (235U) isotope is present at 90 per cent.

This week the International Atomic Energy Agency (IAEA) confirmed that Iran has begun enriching uranium to 20 per cent 235U at its underground plant at Fordow. That level of enrichment is closer than it seems to the 90 per cent needed for a typical nuclear bomb.

Break out

Olli Heinonen of Harvard University calculates that it would take Iran six months to make a bomb starting from the fuel-grade 3.5-per-cent 235U made under UN inspection at the Natanz plant, but only a month starting from 20-per-cent 235U. Such a stockpile means Iran could "break out" and build a bomb "very quickly should it decide to do so", he says.

This possibility is especially problematic for Israel, which has hinted that it will attempt the military destruction of Iran's nuclear infrastructure at any sign that it is making nuclear weapons. The underground plant at Fordow, however, is virtually bomb-proof.

And so to the dead Iranian scientists. Attempts to derail a country's nuclear programme by killing its scientists "are products of desperation", says Tobey – citing a US effort to kill legendary physicist Werner Heisenberg during the second world war, abandoned at the last minute only when the would-be assassin decided Heisenberg was not involved in a Nazi nuclear effort after all...."