A preliminary investigation by Lebanese authorities into the communications devices that blew up in Lebanon this week found that they were implanted with explosives before arriving in the country, according to a letter sent to the U.

Gallant did not take explicit credit, and Israel has been careful not to take public credit for the exploding beepers on Tuesday or the exploding devices on Wednesday.

U.N. peacekeepers in Lebanon urged immediate de-escalation as hostilities rumbled on at the Lebanese-Israeli border on Friday, following Israel's most intense airstrikes in nearly a year of conflict with the Iran-backed Hezbollah.

For millions of Lebanese, this week's mass explosion of pagers and walkie-talkies, with its bloody aftermath, is painfully similar to the horrific explosion four years ago of haphazardly stored ammonium nitrates that tore through Beirut's port,

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Here are the unanswered questions. Some early speculation suggested that the pagers could have been targeted by a complex hack that caused them to explode. But that theory was quickly dismissed by experts.