The roar of sirens echoed across this sun-kissed city Monday afternoon, and in a heartbeat the woman in the pink bikini was out of the pool, shepherding her three young kids to the nearest shelter.

Up above, the vapor trail of a rocket fired from Gaza, just 10 miles down the coast, ripped the clear blue sky.

And then, a boom: The rocket had been shot down.

The kids jumped back in the seaside pool, and their mother returned to her tanning. Through it all, the lifeguard had barely stirred.

Such is the dichotomous reality this week in southern Israel, where residents live under both the terror of a Hamas rocket barrage and the protection of a highly sophisticated antimissile system that has proved remarkably successful at intercepting the incoming fire.

The Iron Dome defense

When Iron Dome works, as it does some 90 percent of the time, the rockets explode overhead, producing a deep boom that Israelis have learned to distinguish from the bang of a direct hit.

The system is widely credited here with allowing Israel to endure more than 1,000 rocket attacks in the past week without a single fatality as of Monday night. It has also allowed residents across the south to carry on with a measure of normality, despite an unrelenting exchange of fire that has claimed more than 185 lives in nearby Gaza.

“I can’t even explain with words how great it is,” said Sivan Hadad, 32, who has lived her entire life in Ashkelon and had grown accustomed to staying indoors when the rockets started flying. “Now I can go out. I still get scared, but not like before.”

To Israeli security officials, the success of Iron Dome is akin to that of the separation barrier between Israel and the West Bank, which they say helped bring an end to an onslaught of suicide bombings in the early 2000s.

The Iron Dome system has rendered rockets so ineffective that Hamas and its allies have, in recent days, been attempting more-creative ways of attacking Israel. Last week, a Hamas commando unit tried to infiltrate Israel by sea before being cut down on the beach by Israeli fire. On Monday, the Islamist militant group launched a drone that hovered over the southern city of Ashdod.

The drone launch was believed to have been the first time that the group has sent an unmanned aerial vehicle into Israeli airspace, after the Lebanese Shiite militia Hezbollah did the same last year. Monday’s drone was shot down by a U.S.-supplied Patriot missile.

“I think they’re getting frustrated,” said Danny Danon, Israel’s deputy minister of defense. “They’re still looking for a success.”

This video, released by the Israel Defense Forces (IDF), shows two methods for warning Palestinian civilians of an upcoming airstrike. The first part of the video features an audio recording of a call made by an IDF representative to a Palestinian citizen, warning them that they should leave the building they are in as it is about to be targeted. The second part shows the Israeli military shooting a small “warning missile” at a building in Palestine designed to warn occupants that the building will soon be destroyed. (Israel Defense Forces)

Iron Dome may be changing Israel’s tactics and calculus, as well. In Israel’s offensive against Hamas in 2008 and 2009, before Iron Dome was implemented, Israel sent in ground troops, dramatically increasing the death toll on both sides. But in another major operation in late 2012, Iron Dome was deployed for the first time and Israel kept its soldiers out of the strip.

It has largely done the same this time.

“If we did not have it and the rockets were falling in Israel, killing people, then the Israeli army would have little choice but to enter Gaza on foot to get rid of the place where the rockets are coming from,” said Amir Peretz, who was defense minister from 2006 to 2007 and is widely seen as the godfather of Iron Dome. “This would mean much more civilian casualties on both sides.”

But critics say the system also has taken some of the pressure off Israel’s leaders to negotiate a peace agreement with the Palestinians.

Iron Dome, Peretz said, is no more than a stopgap.

“In the end, the only thing that will bring true quiet is a diplomatic solution,” he said.

Such an enduring peace appears remote. And in the meantime, Iron Dome has changed the way Israelis experience war.

The system uses highly complex algorithms to chart the path of a rocket from the moment it leaves its launch site in Gaza, calculating almost instantly whether the projectile is headed for a populated area.

If it is, one of the mobile Iron Dome batteries positioned across the country fires and attempts to intercept the rocket. If the rocket is headed toward an open area or toward the sea — as the majority of Hamas’s crudely guided rockets are — Iron Dome lets it pass.

The system, developed with substantial American assistance, has been improved since Israel’s 2012 fight with Hamas and has been more accurate this time around, Israeli officials say. But there are still occasional misses.

On Sunday, a 16-year-old boy riding his bike in this city of 135,000 was critically injured by shrapnel after a rocket slipped through. Local emergency officials faulted the boy for not taking cover when the sirens sounded and say they worry that residents are becoming too complacent about the threat because they think Iron Dome will always protect them.

While some residents of southern Israel have spent the past week shuttling in and out of bomb shelters, others have not seen the need.

“When the sirens sound, I stay in my apartment. I don’t really feel like sitting in a bomb shelter,” said Adi Dahan, a 28-year-old real estate agent who lives in a gleaming new apartment tower with stunning views of the Mediterranean.

The building is one of dozens going up in this prosperous city, which is attracting new residents at a clip of up to 500 every month despite its status as a top Hamas target. In the past week alone, at least 65 rockets have sped toward Ashkelon, and 35 have been shot down by Iron Dome. Four have struck.

Amid the barrage, Dahan said she continues to get calls from people across Israel and from around the world who are eager to move to Ashkelon for the sea views and bargain prices. Because of Iron Dome, the rockets do not seem to worry them much.

“When I show them the south-facing apartments, they say, ‘Oh, that’s where the rockets are coming from.’ But they’re not really nervous,” she said. “I just tell them, ‘If you’re facing the south, you get more sun.’ ”

William Booth in Gaza City contributed to this report.