Vienna ? The U.N. nuclear atomic energy agency said Tuesday for the first time that Iran is suspected of conducting secret experiments whose sole purpose is the development of nuclear arms.

The report is the strongest sign yet that Iran seeks to build a nuclear arsenal, despite claims to the contrary. With Israel threatening a military response, the report opens the way for a new confrontation between the West and Iran.

In its latest report on Iran, the International Atomic Energy Agency outlines the sum of its knowledge on the Islamic Republic’s alleged secret nuclear weapons work, including:

• Clandestine procurement of equipment and design information needed to make such arms;

• High explosives testing and detonator development to set off a nuclear charge;

• Computer modeling of a core of a nuclear warhead;

• Preparatory work for a nuclear weapons test, and

• Developing and mounting a nuclear payload onto its Shahab 3 intermediate range missile — a weapon that can reach Israel, Iran’s arch foe.

Israeli government spokesman Mark Regev said there is a government directive not to comment until Israel has studied the report in depth.

But ahead of the report’s release, Israeli Defense Minister Ehud Barak warned of a possible Israeli military strike against Iran’s nuclear program.

He told Israel Radio that he did not expect any new U.N. sanctions on Tehran to persuade it to stop its nuclear defiance, adding: “We continue to recommend to our friends in the world and to ourselves, not to take any option off the table.”