The outcome and duration of the Middle East war could be determined by the size of Iran's stockpile of drones and missiles compared to the vital air defence munitions held by the US, Israel and Gulf states, analysts and officials have said, writes "The Guardian".
Since February 28 - in response to the US and Israeli attack - Iran has launched more than 1,000 strikes on targets in neighbouring US-allied countries. Because Tehran's air force cannot compete with those of Israel and the United States, Tehran relies on its arsenal of missiles and drones.
The United States and Israel are seeking to destroy as much of Iran's missile arsenal and infrastructure as possible, targeting launchers, storage facilities and personnel.
Stacey Pettyjohn, director of the defense program at the Center for a New American Security in Washington, said the conflict has become "something of a volleying contest" - a military-strategic concept describing the simultaneous exchange of volleys of large numbers of precision-guided weapons between opposing forces.
She said, "the question is who has the deeper caches of key weapons, and the big unknown is how deep Iran's caches are".
According to analysts, Iran is either trying to conserve its stockpile of missiles or simply is unable to launch more.
"Iran has fewer weapons that can reach Israel than it does the Persian Gulf, and many drones aimed at Israel are being intercepted," Pettijohn explained.
She said there may also be "some chaos that the Iranians are dealing with because they are suffering decapitation strikes [killing senior commanders] and therefore are not acting in a coordinated manner. They just take advantage of what they can, when they can," she explained.
Tehran's strategy may be to try to wear down its enemies by undermining the morale of its citizens and increasing the financial costs of the conflict.
Tal Inbar, a senior fellow at the Israel-based Missile Defense Advisory Alliance, said that "there is no such thing as 100% defense." This is a war of attrition... If a single missile hits something like a university, a hospital or a power plant, it can be very costly."
During the 12-day war with Iran last summer, when massive rocket barrages were fired at Israel, Israel reportedly ran out of key weapons.
"In previous wars and conflicts, the duration was determined in part by the amount of [air defense missiles] we had... There can never be enough interceptors," Inbar noted.
All parties to the current conflict acknowledge the importance of the fierce air battle and are working to calm anxious citizens.
The United Arab Emirates issued a lengthy statement denying reports that it was running out of key interceptor missiles. "The UAE... maintains a robust strategic stockpile of munitions, providing sustained interception and response capabilities for extended periods," the statement said.
On March 2, the UAE said it had so far destroyed 161 of the 174 ballistic missiles fired at the country, with the remainder falling into the sea. Of the 689 Iranian drones, 645 were intercepted and eight cruise missiles were destroyed, "causing some collateral damage."
Iranian strikes have also been launched against US military and civilian infrastructure sites in Qatar, Abu Dhabi, Kuwait, Iraq, Bahrain and Oman. International hotels in Dubai were also hit.
Oil infrastructure was damaged in Saudi Arabia, and drones attacked a British military base in Cyprus.
Qatar also released a statement describing the "detection of multiple air and missile targets and the successful interception of the majority of them". The Defense Department said it shot down two Iranian fighter jets, three cruise missiles, 98 of 101 ballistic missiles and 24 of 39 drones.
"It's very difficult to know the level of stockpiles [of these weapons] in the Persian Gulf, but they are burning a lot of them and some tough decisions will have to be made soon about what to defend," said Kelly Grieco, a strategic and military analyst at the Stimson Center in Washington.
Grieco added that "the Iranians know this and that's why their volleys are not as large. They are looking to continue the campaign."
For her part, Stacey Pettyjohn pointed out that if air defense stocks were depleted, it could lead Israel and the United States to stop offensive operations and try to reach some kind of agreement through negotiations.
"The US could withdraw its forces, Israel obviously can't, but the Gulf states are now bearing the brunt and they could continue to be defeated... If Iran runs out of missiles... it may just have to sue for peace and try to survive and possibly rebuild its capabilities over time," Pettyjohn said.
The enormous cost of the weapons in question and their limited availability are also important.
Grieko estimates that intercepting a drone costs five times more than producing one, while the stockpiles of the most advanced weapons made in the US are very limited and can be replenished slowly.