By Lynsey Chutel and Eve Sampson

A second wave of hand-held devices simultaneously exploded in Lebanon on Wednesday (18), killing at least 20 people and injuring hundreds more, one day after 12 people were killed and thousands wounded in a similar attack that targeted members of Hezbollah.

The blasts — which came after Israeli officials said they were ready to step up attacks against the Iranian-backed militia — have heightened concerns that Israel’s long-simmering conflict with the group might escalate into a broader war. Hezbollah and Iran quickly blamed Tuesday’s (17) operation on Israel, an assessment confirmed by US and other officials. Israel has not confirmed or denied responsibility.

With hospitals in Lebanon struggling to cope with the number of wounded, Israel and Lebanon were tensely awaiting a promised retaliation from Hezbollah and its allies.

Here’s what you need to know about the attack and its potential ramifications.

What happened?

Pagers carried by hundreds of Hezbollah fighters began beeping for several seconds at 3:30 p.m. Tuesday with what appeared to be a message from the group’s leadership, according to two officials familiar with the attack. Then they exploded — in grocery shops, on sidewalks, even on a moving motorcycle.

Lebanese officials said 12 people had been killed Tuesday, including a young girl. Hezbollah said that at least eight of its fighters were among the day’s dead and more than 2,700 people were injured in Lebanon — including Iran’s ambassador to the country.

In Syria, at least 14 people were injured, according to the Syrian Observatory for Human Rights, a British-based monitor.

Lebanon’s caretaker prime minister, Najib Mikati, condemned what he characterized as “criminal Israeli aggression” and called it a “serious violation of Lebanese sovereignty”.

A little more than 24 hours after the pagers started exploding, new blasts were reported, including one that interrupted an outdoor funeral for two Hezbollah fighters, a child and a paramedic killed in Tuesday’s attack.

Fires broke out in homes, stores, cars and motorcycles, the country’s emergency service said.

The number of people killed in Wednesday’s attack has surpassed Tuesday’s death toll, according to the Lebanese Health Ministry.

How did the devices explode?

Officials and analysts ruled out malfunctions and said the pagers from Tuesday’s attack appear to have been tampered with before they made it into the hands of Hezbollah members.

Israel hid tiny explosives inside a batch of Taiwanese-branded pagers imported to Lebanon, according to US and other officials briefed on the operation. The explosive material, as little as 1 to 2 ounces, was implanted next to the battery in each pager, two of the officials said. A switch was also embedded that could be triggered remotely to detonate the explosives.

The Tuesday attack affected pagers that were switched on and receiving messages.

The Taiwanese company, some officials named as the supplier, Gold Apollo, sought to distance itself from the devices, saying on Wednesday that another manufacturer with a Hungarian address had made the model targeted in the attack as part of a licensing deal.

The devices that exploded after Wednesday’s attack showed two-way radios that were significantly heavier than the pagers used in Tuesday’s attack, a Times analysis showed, suggesting that the devices may have contained more explosives. A review of three photos and one video identified the devices to be IC-V82 radios with the brand of Japanese company Icom.

Why was Hezbollah using pagers and two-way radios? 

Officials said Hezbollah had ordered more than 3,000 pagers from Gold Apollo, distributing them not just to fighters, but also to rank-and-file members across Lebanon and in Syria and Iran. It was not clear when the pagers were ordered or when they arrived in Lebanon.

Hezbollah has used pagers for years to make its messages harder to intercept. The group’s reliance on pagers increased after Hamas attacked Israel on Oct. 7, when Hezbollah’s leader warned that Israeli intelligence had penetrated the cell phone network, according to security experts.

Analysts said that in trying to guard against one vulnerability, Hezbollah had opened itself to another fatal attack. Abandoning cell phones meant the group also “took out a central means of communication,” said Keren Elazari, an Israeli cybersecurity analyst and researcher at Tel Aviv University.

While the attack will likely incapacitate some members, Hezbollah has a long history of adaptability: It lost many fighters in its last major war with Israel, in 2006, but emerged stronger in the years that followed.

It is unclear where Hezbollah purchased the radios that exploded in Wednesday’s attack. Hezbollah has previously been linked to the IC-V82 by a privately funded group advocating stronger sanctions on Iran, United Against Nuclear Iran.

What happens now?

Hezbollah was quick to pin responsibility on Israel for the attack and warn that there would be “punishment for this blatant aggression,” prompting fears that a simmering conflict between the two could boil over.

The group’s leader, Hassan Nasrallah, is expected to give an address Thursday (19).

Israel and Hezbollah have been trading near-daily cross-border fire since Oct. 7, and Hezbollah, Hamas’ ally, began firing rockets into northern Israel in support.

The violence has driven tens of thousands of people from their homes on both sides of the border and prompted repeated rounds of diplomacy in an attempt to fend off a wider war and more direct Iranian involvement.

The cross-border clashes have intensified in recent months. As Israel scales down its assault against Hamas in the Gaza Strip, it has more of its forces available for a possible offensive in the north against Hezbollah. This week, the country’s defence minister, Yoav Gallant, warned that “military action” was “the only way” to end the conflict.

While the blasts embarrassed Hezbollah and appeared to incapacitate many of its members, they have not so far altered the military balance along the Israel-Lebanon border.

Observers of Hezbollah said the group’s leaders were likely stuck between feeling the need to respond and wanting to avoid an all-out war with Israel that could be catastrophic for both sides.

Will the attacks affect the war in Gaza?

Both Hezbollah and Hamas are backed by Iran, part of a network of proxies that Iran has supported in the region.

Since Hezbollah has tied its attacks on Israel to the war in Gaza, officials had hoped that a cessation of hostilities in the Palestinian enclave might lead to a parallel agreement between Israel and Hezbollah.

US and French mediators, led by Amos Hochstein, a US envoy, have shuttled between Beirut and Jerusalem, preparing the ground for a truce between Israel and Hezbollah in the event of a deal in Gaza.

The blasts might change those calculations and complicate those efforts.

On Wednesday, John F. Kirby, White House national security spokesperson, said the United States was not “in any way” involved in operations that caused the two waves of blasts.

Secretary of State Antony Blinken said Wednesday the United States did not know about the pager attack in advance and was not involved. He said at a news conference in Cairo that the United States has been “very clear about the importance of all parties avoiding any steps that could further escalate the conflict that we’re trying to resolve in Gaza.”

-New York Times