Hezbollah fired rockets into Israel during the 2006 conflict
The Lebanese Shia Islamist movement, Hezbollah, now has rockets capable of reaching Israel's largest cities, the head of the Israeli military has said.
Major General Gabi Ashkenazi told lawmakers Hezbollah's military wing had tens of thousands of rockets, some with a range of more than 300km (186 miles).
This would potentially put the cities of Tel Aviv and Jerusalem within reach.
Last week, Israel's navy seized a ship it said was carrying hundreds of tonnes of weapons destined for Hezbollah.
"While it is calm at the moment - the borders are quiet in the north and the south - it is a misleading calm," the Israeli newspaper Haaretz quoted Gen Ashkenazi as saying.
"Beyond the fences, the terror groups are gaining strength."
Israel and Hezbollah fought a 34-day war in 2006 during which more than 1,200 Lebanese, mostly civilians, were killed. Some 160 Israelis, most of whom were soldiers, also died.
Israel's leader said the weapons on the Francop were for Hezbollah
Israeli forces initially launched air strikes and incursions into Lebanon after Hezbollah abducted two Israeli soldiers. Hezbollah responded by launching rockets onto towns in northern Israel.
UN Security Council resolution 1701, which ended the conflict, included an arms embargo on Lebanon, except for transfers authorised by the Lebanese government or UN.
But many analysts believe Hezbollah has since been rebuilding its arsenal.
Israel holds up two recent large explosions in southern Lebanon as evidence that the group has been stockpiling weapons, in contravention of the resolution.
The UN says there are indications that one of the explosions was at an "actively maintained" arms depot, although Hezbollah says it was a munitions dump.
Israel released a video purportedly showing munitions being removed after a blast in October. Hezbollah said it was debris
It also agrees that the several hundred tonnes of rockets, hand grenades and mortars found on board the Francop last week were being transported from Iran to Hezbollah.
Hezbollah denies any link to the weapons, accusing Israel of "piracy" in seizing the ship.
Maj Gen Ashkenazi's assessment comes a week after Israel's head of military intelligence said Hamas militants in Gaza had test-fired a rocket which had a range of 60km (37 miles).
This would enable Palestinian Islamist group to strike Tel Aviv.