*Iran two to three years from nuclear weapon: think tank*

Iran could be only two or three years away from being able to produce a
nuclear weapon, the head of a leading international security think tank
in London said.

John Chipman, of the International Institute for Strategic Studies
(IISS), said Iran had stockpiled 250 tonnes of uranium hexafluoride
(UF6), which, when enriched, would be enough for 30 to 50 weapons.

But he stressed that Iran still faced other obstacles before it could
build a weapon.

While Iran is "probably" on track to hit a target of producing 3,000
centrifuges -- the machines which enrich uranium -- at its nuclear
facility in Natanz by the end of March, installing them and making them
function properly would be complicated, Chipman said.

"If and when Iran does have 3,000 centrifuges operating smoothly, the
IISS estimates it would take an additional nine to 11 months to produce
25 kilogrammes (55 pounds) of highly enriched uranium, enough for one
implosion-type weapon.

"That day is still two to three years away at the earliest," he said.

Launching the IISS's annual report assessing global military capability,
Chipman added that the "main bottleneck" for producing weapons was
learning how to run UF6 through linked cascades for long periods.

"If Iran overcomes the technical hurdles, the possibility of military
options to stop the programme will increase," he added.

Although US President George W. Bush has said the United States has no
plans to invade Iran, Washington is isolating the Iranian regime over
nuclear suspicions and allegations of complicity in attacks on US troops
in Iraq.

In December, the United Nations Security Council adopted a resolution
imposing sanctions on Iran for its repeated refusal to freeze enrichment
work.

President Mahmoud Ahmadinejad's regime insists it only wants to use
nuclear technology to generate energy, despite fears that it could be
used to build an atomic bomb.

Chipman said that the sheer volume of centrifuges was "a political act,
designed to demonstrate technological achievement at home and defiance
abroad."

He added that having such a high number in place could provide Iran with
a bargaining chip if international negotiations resume.

"Having more centrifuges in place -- even if not operating -- would also
put the programme at a higher plateau in the event negotiations resumed
and Iran made an offer to cap the size," he added.

Iran kicks off 10 days of celebrations Thursday marking the anniversary
of its 1979 Islamic revolution, during which it is thought officials may
announce the start of phase one of nuclear fuel production for
industrial purposes.

But it could face further sanctions later this month when Mohamed
ElBaradei, director general of the International Atomic Energy Agency,
submits a compliance report to the UN Security Council.

Elsewhere in his speech, Chipman lent his voice to those criticising
Bush's troop surge to Iraq, which will see an extra 21,500 military
personnel deployed mainly to Baghdad.

"Simply flooding one area of Iraq, in this case parts of Baghdad, with
troops, neglects the subtler aspects of counter-insurgency doctrine," he
said.

"For a surge in troops to be sustainable, it has to be married with the
second stage of the process."

This meant building up administrative capacity and establishing the rule
of law, he added.