BEIRUT -- Syria will supply "game-changing" weapons to Hezbollah, the Lebanese militant group's chief said Thursday, less than a week after Israeli airstrikes on Damascus targeted alleged advanced Iranian missile shipments bound for Hezbollah.
Israel has signaled that it will respond with airstrikes to any future weapons shipments, meaning it could quickly get drawn into Syria's civil war if the Hezbollah chief's declaration is more than an empty threat.
In a related development, Israeli security officials said Thursday that they have asked Russia to cancel the imminent sale of an advanced air defense system to Syria. The officials said Israel shared information with the United States in hopes of persuading Russia to halt the planned deal to provide S-300 anti-aircraft missiles. The Israeli officials spoke on condition of anonymity because they were not authorized to brief reporters.
In Rome, U.S. Secretary of State John Kerry said Thursday that the transfer of advanced missile defense systems from Russia to Syria would be a "destabilizing" factor for Israel's security. Mr. Kerry said the United States has expressed concerns about what such defensive systems in Syria would mean for Israel's security, though he declined to address what the missiles might mean for Syria's civil war.
Tension has been rising in the region since Israel struck targets inside Syria on Friday and Sunday. Hezbollah and Israel fought several battles in the past three decades, including a 34-day war in 2006 that left some 1,200 Lebanese and 160 Israelis dead.
Israel has largely tried to stay out of Syria's 26-month-old conflict. It never acknowledged the airstrikes, but Israeli officials have signaled that Israel's air force would strike against any shipments of strategic missiles that might be bound for Hezbollah. Israel and Hezbollah have been exchanging threats over the past months.
Israeli officials say the Lebanese militant group has tens of thousands of rockets, though most of them are unguided. The shipments targeted last week included precision-guided missiles, the officials said.
Hezbollah chief Sheik Hassan Nasrallah has said in the past that his group has missiles that can strike anywhere in Israel, including as far south as the Red Sea resort of Eilat.
Meanwhile, Hezbollah and Iran have become increasingly involved in Syria's civil war, supplying troops and military advisers to help Syrian President Bashar Assad fight armed rebels trying to oust him.
Sheik Nasrallah spoke Thursday to mark the 25th anniversary of the founding of Hezbollah's radio station, Al-Nour, in a speech televised in Beirut. The militant leader has rarely appeared in public since the 2006 war, for fear of being targeted by Israel.
Sheik Nasrallah said Hezbollah could expect strategic weapons from Syria in the future. "Syria will give the resistance special weapons it never had before," he said. "We mean game-changing."
Sheik Nasrallah said the weapons shipments were Syria's response to the Israeli airstrikes. "This is the Syrian strategic reaction," he said. "This is more important than firing a rocket or carrying out an airstrike" against Israel.
The military alliance between Syria and Hezbollah will continue, the Hezbollah chief said. "We in the Lebanese resistance declare that we stand by the Syrian popular resistance and give our material and moral support, and cooperate and coordinate in order to liberate the Syrian Golan," he said. Israel captured the Golan Heights from Syria in the 1967 Mideast war and later annexed the strategic plateau.
Asked about Sheik Nasrallah's declaration, Israeli Foreign Ministry spokesman Yigal Palmor said: "We don't respond to words. We respond to action."
Earlier Thursday, the Assad regime said it welcomed efforts by the United States and Russia to try to bring the two sides in the civil war to the negotiating table before the end of the month. Syrian Information Minister Omran al-Zoubi said the government is willing to consider any proposals for a political solution of the conflict, while it retains the right to fight "terrorists," the regime's term for the opposition fighters and their supporters.
Mr. Zoubi did not specifically mention the U.S.-Russian initiative in his brief remarks to reporters in Damascus, carried by the state-run SANA news agency.
The main Western-backed opposition group, the Syrian National Coalition, said Wednesday that it welcomes the U.S.-Russian effort to reach a political solution, but any transition must begin with the departure of Mr. Assad and regime officials.