Why hasn’t Iran attacked Israel to avenge Hamas’s leader?

Nearly a month has passed since Ismail Haniyeh was assassinated in a Tehran guest house belonging to the Iranian Revolutionary Guard Corps. Iran blamed Israel for the Hamas leader’s death from a remotely denoted explosive, which appears to have been planted nearly two months earlier. Two IRGC operatives were reportedly responsible for planting that explosive.

Despite Israel refusing to confirm or deny that it had a hand in Haniyeh’s death, the Iranian government has vowed revenge. Iran has rejected pleas from both the U.S. and European leaders not to attack Israel, which could lead to an expansion of the current hostilities, thus far limited to the war in Gaza and limited exchanges between Israel and Hezbollah. Yet, despite its threats, Tehran has yet to act.

Officially, the Iranians have said that they will not respond if there is a cease-fire in Gaza, but the fighting in the enclave continues. Moreover, even if, as Secretary of State Antony Blinken has asserted, Israeli Prime Minister Benjamin Netanyahu has accepted the latest American cease-fire proposal — and it is unclear whether Netanyahu has done so unconditionally — Hamas has rejected it.

Hamas leader Yahya Sinwar has every reason not to agree to a cease-fire. That more innocent Palestinian civilians — many of whom have no truck with Hamas — are being killed on a daily basis is, as he has stated, of no concern to him. On the other hand, the longer the fighting continues, the greater his hope that Iran will indeed attack Israel.

Ironically, Netanyahu might be hoping for the same result, so as to drag the U.S. into a war with Iran. Indeed, he has been seeking active American support for a strike against the Islamic Republic for years.

The Biden administration, like its predecessors, has promised to defend Israel against an Iranian attack but has made clear that it will not support an offensive Israeli operation against Iran. When Tehran launched a 300-strong missile and drone barrage against Israel on April 13, the U.S. and also Britain, France and several Arab states worked together to shoot down the incoming weapons. Biden, and reportedly Britain and France, are prepared to do so again.

To that end, Secretary of Defense Lloyd Austin announced on Aug. 11 that Washington was sending the USS Abraham Lincoln, an aircraft carrier supporting F-35C and F/A-18 Block III fighter jets, together with the five guided-missile destroyers that constitute destroyer squadron 21, to join the carrier Theodore Roosevelt, other Navy and Marine afloat units, and about 80 land-based aircraft already in the Middle East region. Even as the Iranians had yet to show their hand, Austin announced this week the Lincoln strike group’s arrival on station.

Although the strike aircraft could operate offensively against Tehran, if refueling were made available along the way, their presence is strictly defensive. That, however, is not the case for the guided-missile nuclear submarine USS Georgia, which Austin also announced was deploying to the region.

The Georgia offers little in the way of defenses against drones and missiles — it is an offensive weapon. It is armed with 154 long-range Tomahawk Land Attack Missiles whose latest version has a range of 1,600 kilometers. That range is long enough to let the submarine fire at the Iranian oil terminals on Kharg Island from off the Israeli coast.

Moreover, depending on the nature of the damage inflicted on these critical Iranian oil facilities, it could be exceedingly difficult for the Iranians to determine that Tomahawks have struck their territory until after the attack, and perhaps not even then. In any event, because of both the range of its missiles and its stealthy operations, the Georgia significantly bolsters the American deterrent against an attack on Israel.

At this stage, it is not at all clear that President Biden would actually order a strike against Iran, even employing Tomahawks launched from the Georgia. Like an aerial attack, this risks both a widening of Mideast hostilities and American involvement in an all-out military confrontation with Iran that Washington has been avoiding for years.

On the other hand, despite being a lame-duck president with little prospect of having major legislation pass Congress, Biden has far fewer constraints should he order an attack on Iran.

That possibility, in and of itself, constitutes an additional deterrent that the ayatollahs must take into account. And it may be a major reason why, despite all of their bluster, the Iranians still proceed with caution, despite their fury at the loss of face that Israel has caused.

Dov S. Zakheim is a senior adviser at the Center for Strategic and International Studies and vice chairman of the board for the Foreign Policy Research Institute. He was undersecretary of Defense (comptroller) and chief financial officer for the Department of Defense from 2001 to 2004 and a deputy undersecretary of Defense from 1985 to 1987.