TEL AVIV, Israel — The recent unveiling of a large Iranian satellite launcher with the potential for doubling as an ICBM has injected additional anxiety into rapidly escalating international tension over Tehran’s nuclear weapons program.

The new Simorgh is a two-stage liquid-fueled booster with an estimated takeoff weight of 87 tons, nearly four times that of the solid-fueled Sejil and double the weight of the Safir vehicle used to deliver Iran’s first satellite into space.

Iran unveiled a full-scale mock-up of the system in Feb. 3 National Space Day ceremonies broadcast live on state-run television. Iranian President Mahmoud Ahmadinejad and Defense Minister Ahmad Vahidi presided over the event, which also featured the launch of the Kavoshgar-3 (Explorer) rocket and its live payload — a turtle, a rat and worms — into space. No first launch date was announced for the Simorgh, but U.S. and Israeli experts say that if Iranian claims are true, and the engine is already developed, it could be readied as a headline event for next February’s National Space Day. In February 2009, Iran marked the occasion with the Safir-2’s successful deployment of the Omid research satellite into low Earth orbit.

The Simorgh features a first stage built from bundling four separate 64,000-pound-thrust engines and a 30,000-pound-thrust engine as a second stage. Although Iran has acknowledged a lift capacity of just 100 kilograms, Nader Uskowi, a Washington-based consultant and blogger on Iran, said optimization of its current design should allow for delivering a 700-kilogram payload into low Earth orbit.

Despite its size, Simorgh as currently designed falls far short of meeting ICBM-class thrust-to-payload requirements, experts say. “This mammoth cannot carry a reasonable re-entry vehicle the 10,000 kilometers needed to reach the United States,” said Uzi Rubin, a former director of Israel’s Missile Defense Organization who consults internationally on missile development programs.

“It’s not the capability that’s significant, but the audacity of the whole thing,” said Rubin. “These guys are thinking big time. They’re diligently following a road map that includes the ability to project strategic power beyond this region.”

Given the rigorous pace and demonstrated achievements of Iran’s missile development program, the Simorgh “could be Iran’s road to an ICBM,” said Tal Inbar, director of Israel’s Fisher Institute Space Research Center. “For now, it’s untested and extremely inefficient, but in the future, it could be configured to deliver a crude payload to the continental United States,” he said.

David Wright, a veteran analyst with the Cambridge, Mass.-based Union of Concerned Scientists, estimated that if employed as a ballistic missile, the Simorgh would have a range of 4,000 kilometers when carrying a 1-ton warhead. “But to get to ICBM ranges, they’d have to reduce payload to about 100 kilograms,” he said.

“In itself, Simorgh is not an ICBM, but there is potential for working up to that in time,” Wright said. “Now that they’ve developed a much more capable first stage, the next step is to scale up an efficient second stage.”

In a Feb. 10 interview, Wright said Simorgh’s first stage was very similar, if not identical, to North Korea’s three-stage Taepodong-2. According to Wright’s calculations, Simorgh should weigh “up to 70 tons,” much less than Israeli estimates.

The public showcasing of space technologies followed similar high-profile debuts of air- and ground-combat systems staged during the 10-day Dawn celebrations commemorating Iran’s 1979 Islamic Revolution. Ahmadinejad capped the annual demonstrations of national pride by announcing plans to increase uranium enrichment from current commercial levels of 3.5 percent to up to 20 percent.

Although weapons-grade uranium requires a minimum enrichment level of 90 percent, experts say once Iran reaches 20 percent, it can very rapidly breach the so-called weaponization threshold. “It depends on what the Iranians decide to do. If they enrich to 20 percent, and then use that as a starting point for further enrichment, it would substantially shorten the time to get to weapons-grade levels,” said Ivan Oerlich, vice president of the Federation of American Scientists’ Strategic Security Program.

U.S. President Barack Obama denounced expanded enrichment plans as yet another manifestation of “Iran’s misbehavior.” In a Feb. 9 briefing to White House reporters, Obama said Western leaders are preparing to confront Iran within weeks with “a significant regime of sanctions” for continued defiance of U.N. and International Atomic Energy Agency directives.

Simorgh came as a surprise to Israeli and U.S. experts, who expected Iran to increase lift capacity by adding a third stage to the liquid-fueled Safir-2 or its solid-fueled Sejil-2 vehicles. “It came as a surprise. There wasn’t any indication they were going in that direction,” said Inbar.

“Most analysts expected development of a three-stage Sejil as the next logical step in Iran’s missile development program,” said Uskowi.

Initial Israeli assessments have identified four separate Shehab 3B rocket motors as the Simorgh’s clustered first stage. The rocket also has four vernier thrusters used for steering, each with 7,500 pounds of thrust, that could have come from the Russian BM-25 artillery rocket or the Russian SS-N-7 submarine-launched missile.

Israeli analysts say the Simorgh’s second-stage motor and launch vehicle shroud are similar to Safir, although the shroud itself features a unique composite structure whose origin is unknown. “It’s not a knockoff of a North Korean launcher, but more of an upgrade of their own Safir,” an Israeli analyst said.

Dimensions calculated by Israelis from publicly released Iranian photos indicate a length of 27 meters, with a first-stage diameter of 2 meters to 2.3 meters and a second-stage measuring 1.25 meters in diameter.