JERUSALEM — Since Friday, the same dramatic exchange has played out more than a half-dozen times over the skies of Israel: A barrage of Iranian ballistic missiles come streaking in. A flurry of Israeli defensive interceptors rise to knock out most, but not all, of the incoming volley.

One key question is how long each side can keep up. The answer may affect how long the conflict could last.

Israeli intelligence officials estimated that Iran had about 2,000 missiles capable of traveling 1,200 miles to hit Israel, but a significant fraction was destroyed the moment Israel’s covert operatives in Iran and its fighter jets launched a surprise attack early Friday, kicking off the conflict.

Since then, Israeli military officials say that Iran has launched roughly 400 missiles from its remaining stockpile and Israeli strikes have eliminated 120, or one-third, of Iran’s missile launchers. Moreover, Israeli officials announced Monday that they had attained air superiority over Tehran ahead of schedule, meaning they could further limit the Iranian forces’ ability to carry out launches.

Already, the intensity of Iran’s barrages appear to be sharply dropping. After firing more than 150 missiles on the first night of the conflict, Friday, Iran fired a barrage of just 10 on Tuesday afternoon.

“Iran has to make a very, very difficult calculation, because they have a limited amount of missiles, and considering the rate of fire, they cannot replenish in real time,” said Fabian Hinz, a military analyst with the International Institute for Strategic Studies. Hinz noted that even the 150 missiles fired Friday night were less than the 200 Iran fired at Israel in October in retaliation for Israel’s assassination of Hamas and Hezbollah leaders.

Even so, Israeli analysts caution that more than half of Iran’s arsenal remains intact, and an unknown quantity of missiles may be hidden in underground depots.

And while Israel has significantly degraded Iran’s attack capabilities, mounting a defense has been costly for Israel. The Marker, a leading Israeli financial newspaper, reported that missile defense costs Israel as much as 1 billion shekels, or roughly $285 million, a night.

As a result, observers say, a long war of attrition between Israel and Iran may not be possible — at least at the current intensity.

Without resupplies from the United States or greater involvement by U.S. forces, some assessments project Israel can maintain its missile defense for 10 or 12 more days if Iran maintains a steady tempo of attacks, said an individual briefed on U.S. and Israeli intelligence assessments, adding that as early as later this week, Israel’s systems may only be able to intercept a smaller proportion of missiles because of a need to ration defensive munitions. “They will need to select what they want to intercept,” said the individual, who spoke on the condition of anonymity to discuss a sensitive matter. “The system is already overwhelmed.”

Tal Inbar, an Israeli missile expert affiliated with the Missile Defense Advocacy Alliance in Virginia, noted that in 2014, Israel sought a ceasefire with Hamas days before it ran out of air defense interceptors. The level of interceptor stocks is a highly sensitive subject in Israel, but “it could be a factor in a ceasefire” this time as well, Inbar said.

Israel employs a multilayered air defense system, consisting of its famous Iron Dome, which intercepts lower-altitude rockets; the David’s Sling and Arrow systems; and expensive Patriot and THAAD missile defense systems delivered from the United States.

Inbar said a problem for Israel is that it largely relies on the relatively expensive Arrow system, which fires missiles that cost $3 million each, to counter attacks from Iran. While inexpensive and mass-produced Iron Dome interceptors are useful against rudimentary rockets fired by Hamas, the Iron Dome is as ineffective as “shooting a 9-millimeter pistol” at heavy Iranian missiles that hurtle through the outer atmosphere at several times the speed of sound, Inbar said.

On Friday night, Israeli air defenses failed to stop Iranian missiles that narrowly missed the headquarters of the Israel Defense Forces but slammed into central Tel Aviv. On Sunday night, an Iranian missile took a major oil refinery near Haifa offline.

And on Tuesday morning, videos filmed from nearby and posted on social media, which The Post verified, showed four impacts from Iranian missiles in the vicinity of Israel’s intelligence headquarters, north of Tel Aviv. None of the four appeared to strike Mossad headquarters, landing hundreds of meters away, but one impacted inside Camp Moshe Dayan, a nearby site that reportedly hosts Israel’s military intelligence headquarters and Unit 8200, the country’s premier signals intelligence unit.

Iran’s state media reported claims made by Iran’s Islamic Revolutionary Guard Corps that it successfully killed Israeli intelligence and military officials, but those claims could be confirmed. The IDF did not immediately respond to a request for comment.

As of Tuesday, the Israeli government said that only 35 out of 400 missiles fired by Iran made impact — an interception success rate of more than 90 percent. Twenty-four civilians have been killed, with more than 600 injured, the government said.

Iranian authorities said that 224 people had been killed by Israeli strikes as of Sunday, the most recent figures available. They did not differentiate between military and civilian casualties. In several cases, Israeli missiles and drones have struck densely packed apartment buildings to kill Iranian military officials and nuclear scientists in their homes. On Monday, Israel also struck the headquarters of Iran’s state broadcaster after Defense Minister Israel Katz pledged that “the mouthpiece of Iranian propaganda” would “disappear.” After the strike, the Israel Defense Forces said it had targeted an Iranian military “communication center” but did not offer evidence of a military presence at the location.

Jim Lamson, a former intelligence analyst focused on Iranian munitions and now a senior research associate at the Middlebury Institute’s James Martin Center for Nonproliferation Studies, said Iran’s missile capabilities will continue to decline because Israel is now targeting its production facilities.

“Assuming their regime doesn’t change, or assuming they don’t agree to give up their missiles as part of a ceasefire, they’re going to have a huge problem reconstituting their ballistic missile forces,” Lamson said. “That is going to be a big result of how much Israel is able to damage and destroy their production facilities for missiles.”