Barack Obama may be widely regarded at home as the least pro-Israeli president in decades, but he has secretly okayed giving the Jewish state a bunch of special bunker-busting bombs – ideal for destroying Tehran’s ruling mullahs’ nuclear ambitions and so powerful that George W. Bush blocked handing them over.

Capable of penetrating deep beneath the surface, the bunker-busters would be crucial for any air strikes at Iran nuclear sites. Mr. Netanyahu has wanted the bunker-busters for years and, as first reported by Newsweek, Mr. Obama agreed to hand over 55 of the sophisticated and powerful weapons.

Given Israel’s track record of pre-emptive bombing strikes to destroy nuclear sites in neighbouring nations and Iran’s ambitious and suspicious nuclear program, the American bunker-busters may increase the chance of another Middle East war. Iran’s unpredictable and bellicose President Mahmoud Ahmadinejad has vowed to wipe Israel off the map. Iran continues to defy international sanctions with a clandestine nuclear program. Meanwhile, Mr. Netanyahu now has the means to carry out his threat that “Iran will not acquire nuclear arms, and this implies everything necessary to carry this out.”

Israel also has twice launched pre-emptive and devastating air strikes to destroy Arab nuclear reactors before they could produce weapons-grade bomb stock. In 1981, a daring long-distance strike destroyed an Iraqi reactor, ending Saddam Hussein’s pursuit of nuclear weapons.

In 2007, Israeli warplanes bombed a Syrian reactor of North Korean design. Striking Iran, both further away and further along the nuclear-weapons development path and with widely dispersed and deeply-buried sites, would be more challenging militarily. The bunker-busters may be a hammer Israel can’t use unless it has the tacit approval of Washington. It’s not clear if Mr. Obama retained the right to approve any use of the bunker-busters.