JERUSALEM—Israel joined the U.S. in expressing concerns about Russia’s military buildup in Syria ahead of a planned meeting in Moscow on Monday between Prime Minister Benjamin Netanyahuand Russian President Vladimir Putin, Israeli officials said.
“Once we understand exactly what Russia intends to do in the arena and exactly what it plans to move into it, whether infantry or air forces, or others…we’ll know what needs to be done,” Yossi Cohen, Mr. Netanyahu’s national security adviser, told Israel Radio on Friday.
He said senior Israeli army officers would be part of the Israeli delegation to Moscow.
The Israeli government has sought to avoid taking sides in the Syrian conflict, saying it is solely concerned with the effect of the fighting on Israel’s security.
Israeli officials have repeatedly voiced concern that advanced Russian weapons supplied to Syria could end up in the hands of militant groups involved in the fighting there.
Israel conducts routine surveillance missions over Lebanon to monitor the activities of Iran-backed Hezbollah, which along with Russia supports President Bashar al-Assad’s regime.
Mr. Cohen added that the Israeli team wanted “to clarify with the Russian side their intentions and possible implications for Israel, and the required coordination between us in the future, should it be necessary.”
In a major military escalation in the region, Russia has moved jet fighters to a base in Syria for the first time, U.S. defense officials said on Friday. The deployment came hours before U.S. Defense Secretary Ash Carter spoke with his Russian counterpart, a conversation designed in part to help avert a confrontation between American and Russian forces.
In London on Saturday, U.S. Secretary of State John Kerry also raised questions about Russia’s intentions in Syria, and urged Moscow to help bring Mr. Assad to the table for serious negotiations about a political transition as world powers seek a solution to the crisis. Mr. Kerry added that the U.S. would accept a resolution to the Syrian war that allowed Mr. Assad to remain in place for a period before stepping down. Previously, Washington had insisted Mr. Assad should step down before a transition government takes over, leading eventually to free and fair elections.
A U.S.-led coalition has been carrying out airstrikes against Islamic State in Syria and Iraq for a year. Like the U.S., Israel is worried the positioning of Russian fighter jets and surface-to-air missiles in Syria could lead to inadvertent confrontations with its own missions over Lebanon and Syria, where Israel enjoys overwhelming air superiority.
Israeli aircraft have also bombed targets in Syria described as stockpiles or convoys of advanced weapons, including sophisticated Russian-made surface-to-air missiles thought to have been be destined for Hezbollah in Lebanon. Israeli officials have described the advanced antiaircraft systems as “game-changing” because they would challenge Israel’s air superiority in the region.
An announcement last week of Mr. Netanyahu’s visit to Moscow said he would raise “the threats posed to Israel by the increased flow of advanced war materiel to the Syrian arena, and the transfer of deadly weapons to Hezbollah and other terror organizations.”
Along with combat aircraft and an air-defense system, the Russian buildup at a base near Latakia, Syria, has included tanks, armored personnel carriers and artillery, American officials said. Russian officials have described the buildup as defensive and part of Moscow’s routine military support for the Syrian government.
Israeli forces have on several occasions struck Syrian army positions near the Israeli-held Golan Heights after rockets fired by militants and errant shells from the fighting in Syria have landed in Israeli-controlled territory.
Hundreds of Syrians wounded in fighting between rebels and Syrian government forces near the Golan Heights frontier have been taken to Israel for hospital treatment, in what has been described as a purely humanitarian effort.
While Israel’s former defense minister, Ehud Barak, welcomed the prospect of Mr. Assad’s ouster in the early stages of the Syrian conflict, Israeli leaders have since avoided commenting on what Mr. Assad’s fate should be in any future political solution.
—Jenny Gross in London contributed to this article.