In his UN address on September 27, Prime Minister Benjamin Netanyahu described the advances that had transpired in the Iranian nuclear program. He broke down the progress Iran has been making into three stages which mark the extent to which the uranium the Iranians have in stock contains higher percentages of the fissile isotope U-235: a first stage in which they produced low-enriched uranium (3.5 percent U-235), a second stage in which they produced medium-enriched uranium (20 percent U-235), and a third stage in which they hope to reach high-enriched or weapons-grade uranium (90 percent U-235). What the prime minister disclosed was that the Iranians have completed the first stage.

To make his point, he characterized this first stage as “70 percent of the way there,” because nuclear physicists explain that enriching uranium feedstock to the 3.5 percent level requires 70 percent of the total energy needed to manufacture weapons-grade uranium for a bomb. Similarly, once Iran reaches the next stage of enrichment – which is 20 percent U-235 – then it has already used 90 percent of the energy needed to make a bomb, so one could say that it is 90 percent of the way there. Unfortunately, despite six UN Security Council resolutions since 2006 which prohibited Iran from enriching uranium even to the low-enriched level, Iran went ahead in 2010 and began to enrich to the 20 percent level, placing itself in a far better jumping-off point to reach a bomb. Britain’s foreign secretary, William Hague, who has responsibility for the British intelligence agencies, has estimated that the 20 percent enrichment – that brings Iran 90 percent of the way to a bomb – cuts the last leap to weapons-grade uranium to half the time in comparison with starting at the 3.5 percent level alone.

Iran always tries to come up with seemingly legitimate excuses for uranium enrichment. It argued that it needs 3.5 percent enrichment for electricity production, though its only reactor for that purpose, situated at Bushehr, is fueled by Russian-supplied uranium. No red line was drawn by the international community to halt this action. Then Iran claimed it needed 20 percent enriched uranium for manufacturing medical isotopes at the Tehran Research Reactor. Yet the head of the Iranian Atomic Energy Organization disclosed that Iran has enough 20 percent uranium for at least seven years or more. Again, Iran started mass production of this medium-enriched uranium and the world did not effectively find a way to stop it, despite the impressive sanctions that have been implemented. Now the Iranians have begun to argue that they are planning to use nuclear energy for their submarines and surface ships, requiring them to go up to 90 percent enrichment. Once Iran has a stock of 90 percent enriched uranium, they will be quickly crossing the nuclear weapons finish line.

Prime Minister Netanyahu explained why he is stressing uranium enrichment and not the actual production of the warhead. Nuclear warheads are manufactured in relatively small workshops that are difficult for intelligence agencies to monitor. Moreover, under the 1968 Nuclear Non-Proliferation Treaty, the International Atomic Energy Agency (IAEA) has access to Iran’s large enrichment facilities at Natanz and Fordow (Qom). Iran’s weapons workshops, in places like Parchin, are closed to the international community. The IAEA has requested access but been denied. Back in April 2011, former U.S. Secretary of Defense Robert Gates warned on “Meet the Press” that there are aspects of the Iranian program that U.S. intelligence agencies might not catch in time: “If their policy is to go to the threshold but not assemble a nuclear weapon, how do you tell that they have not assembled?”

Thus, Prime Minister Netanyahu stressed that halting Iran’s drive for nuclear weapons must be based on the progress in their enrichment program and not await the assembly of a warhead which no security agency can be certain it will detect in time. As a result, he spoke about drawing a “red line” before Iran completes the second stage of enrichment and has amassed enough 20 percent-enriched uranium so that within months or weeks it can manufacture its first atomic bomb.