The Iran-backed Hezbollah movement said Monday it had downed and seized an Israeli drone as it flew across the Lebanese border, a week after a flash confrontation between the arch-foes.
Israel's army said a drone it was operating "fell" in Lebanon on Sunday. In what appeared to be a response, an air strike at "around midnight" killed 18 pro-Iranian fighters in eastern Syria, a monitor said.
The Syrian Observatory for Human Rights could not confirm whether that raid was Israeli.
Later Monday, the Israeli army said rockets had been fired from Syria but failed to reach their targets.
Hezbollah had issued a statement saying that some of its fighters "confronted with the appropriate weapons an Israeli drone" heading towards the Lebanese border village of Ramyeh overnight.
The Shiite militant group said it subsequently retrieved the device, but did not provide pictures.
An Israeli army spokeswoman told AFP a drone "fell" in Lebanese territory, adding that "there is no risk of a breach of information".
The incident was a sequel to an escalation between the two foes that started on the evening August 24 when an Israeli strike killed two Hezbollah operatives in Syria.
Israel said that strike was to prevent a drone attack on its territory by an Iranian force.
The operation was followed hours later by what Hezbollah described as an Israeli drone attack on its Beirut stronghold.
That led to an escalation in rhetoric and heightened fears of all-out conflict between Hezbollah and Israel, whose main allies Iran and the United States, respectively, are also at loggerheads.
On September 1, Hezbollah fired anti-tank missiles at an Israeli military vehicle and battalion headquarters and Israel responded with a salvo of artillery shells.
- Strike in Iraq -
Analysts said the cross-border exchange, which caused no injuries, was a highly choreographed move aimed at flexing muscle without igniting war.
Hezbollah had warned last week that its actions were only a response to the late August strike in Syria and not to the drone incident in Beirut, for which separate retaliation was to come.
Sources close to the organisation had said its fighters would down an Israeli drone over Lebanon at the first opportunity.
Hezbollah's apparently successful neutralisation of a drone overnight could have marked the end of the latest cycle of attacks and reprisals.
But the Syrian Observatory for Human Rights reported that, probably moments later, a strike by an unidentified aircraft killed 18 pro-Iranian fighters in eastern Syria.
"Their nationalities have not yet been determined," said the Britain-based monitoring group, which has a network of sources across Syria.
The strike took place in the region of Albu Kamal, a town which lies along the Euphrates, on Syria's eastern border with Iraq.
- Multiple fronts -
Albu Kamal lies in Deir Ezzor province which covers much of Syria's remote eastern desert, where the Islamic State group's so-called "caliphate" made its last stand this year.
Control of the area is split between US-backed Kurdish fighters and groups aligned with the Damascus regime, which is supported by Iran and Russia.
Neither Israel nor the US-led coalition, which carries out air strikes in the area against jihadist sleeper cells, commented on the incident.
In June 2018, strikes near the Iraqi border killed 55 pro-regime forces, mostly Syrians and Iraqis.
An American official said at the time that Israel was responsible, but the Jewish state declined to comment.
An Israeli military statement said Monday that rockets had been fired from Syria but all failed to hit Israeli territory.
"The rockets were launched from the outskirts of Damascus by Shiite militia operatives operating under the Iranian Quds Force," it said.
The force is the elite branch of Iran's Revolutionary Guards and is commanded by Qassem Soleimani, the mastermind of Tehran's military strategy in the region.
Israel, which has vowed to keep weakening Iran so long as it continued to develop weapons that threaten the Jewish state, has launched attacks against a variety of targets.
It has carried out operations against Iranian forces and Tehran's proxies in Lebanon, across Syria and in Iraq.