Israeli airstrikes killed 12 people in eastern Lebanon, according to a Lebanese security source - the attacks being the deadliest in the area since the US-brokered ceasefire between the two countries last November.
The Israeli military said the airstrikes targeted training camps used by Hezbollah and warehouses it used to store weapons in the Bekaa Valley region.
Bachir Khodr, governor of the Bekaa region, said seven of the dead were Syrian nationals.
Israel dealt Hezbollah heavy blows in last year's conflict, killing its leader Hassan Nasrallah along with other commanders and destroying much of its arsenal.
Israeli Defence Minister Israel Katz said Tuesday's strikes sent a "clear message" to Hezbollah, accusing it of planning to rebuild the capability to raid Israel through the Radwan force.
Israel "will respond with maximum force to any attempt at rebuilding", he said. He added that strikes were also a message to the Lebanese government, saying it was responsible for upholding the ceasefire agreement.
Hezbollah condemned the Israeli attack on Bekaa Valley, describing it as a "major escalation of ongoing Israeli aggression against Lebanon". It made no mention in its statement on whether some of its fighters were killed in the strikes.
There was no immediate public response from the Lebanese government.
The US has submitted a proposal to the Lebanese government aimed at securing Hezbollah's disarmament within four months in exchange for Israel halting air strikes and withdrawing troops from positions they still hold in south Lebanon.
Under the terms of the ceasefire brokered by the US and France, Lebanon's armed forces were to confiscate "all unauthorized arms", beginning in the area south of the Litani River - the zone closest to Israel.

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