MOSCOW — Prime Minister Benjamin Netanyahu of Israel visited Moscow on Thursday seeking reassurance from President Vladimir Putin of Russia that his country’s presence in Syria would help Israel block arch-nemesis Iran from taking advantage of the chaos to position itself permanently on Israel’s northern border.
Until now, the Israeli government has stayed relatively quiet about developments in the six-year-old conflict raging in neighboring Syria, acting militarily only when it feels its security threatened. But now, as President Bashar Assad of Syria receives a boost from the strategic alliance between Russia and Iran, Tehran’s expanding influence across the region is causing alarm in Israel.
At the start of his meeting with Putin, Netanyahu noted the significant progress made by Russia and other players in the region in fighting Islamist militant groups, including the Islamic State and Al Qaeda. He added, however, that ‘‘the victory over the terrorism of ISIS cannot lead to an upsurge in terrorism by Iran and its proxies. We will not exchange terrorism for terrorism.’’ ISIS is an acronym for the Islamic State.
Although Russia is unhappy with some of Iran’s strategic objectives in a postwar Syria, it is unclear how far Putin would go in supporting Israeli action to prevent Iran from building a sphere of influence from Tehran to Lebanon, via Syria and Iraq.
‘‘Syria is at a crossroads right now. On one side, there is a cease-fire that seems to be holding and Assad has managed to regain control of parts of his country. Israel is worried that Iran and its proxies will gain a permanent foothold in Syria,’’ said senior minister Tzachi Hanegbi of Israel, a close ally of Netanyahu’s.
Ever since Russia entered Syrian territory two years ago, Israel has repeatedly emphasized to Putin its red lines regarding Iran and the groups it supports — Lebanon’s Hezbollah and other Shi’ite militias involved in the fighting in Syria.
Netanyahu has visited Moscow four times over the past 1½ years, and the two sides have struck cooperation agreements aimed at preventing confrontations between their warplanes in Syrian airspace.
With rapid changes on the ground, however, Hanegbi said Israel feels it is time to focus on the future.
In its official statements, Moscow has been unwilling to make predictions about what would happen with Iran’s military buildup after the end of hostilities in Syria.
Deputy Foreign Minister Mikhail Bogdanov of Russia, in an interview with the newspaper al-Hayat on Sunday that was quoted by the Interfax news agency, said any decision on the withdrawal of Iranian forces would rest with Syria’s leaders.
‘‘The lawful authorities who will be lawfully chosen in Syria would be the ones with the right to demand the withdrawal of all foreign powers from the country,’’ Bogdanov said.
This official stance reflects the reality that Putin has neither the ability nor the intention to exclude Iran from a settlement in Syria, not when Iran’s role in supporting Assad far exceeds that of Russia’s, said Vladimir Frolov, a foreign policy analyst based in Moscow.
During the course of Syria’s war, Iran has provided billions of dollars to shore up Assad’s regime and contributed much of the manpower that has sustained the depleted Syrian army’s capabilities, in the form of Shi’ite militias recruited from the region and elsewhere.
In the process, Iran has significantly expanded its reach across Syria, giving it new strategic depth in any future conflict with Israel. Members of the Iranian Revolutionary Guard Corps are now present along the 1967 cease-fire line with Israel in the Golan Heights, putting them directly opposite Israeli troops for the first time.
Hezbollah, which has fought wars with Israel and has an estimated 6,000 to 8,000 fighters in Syria, is also active in the Golan.
On Wednesday, an Iranian-allied Shi’ite militia from Iraq, Hezbollah al-Nujaba, announced that it had established a new unit, the Golan Liberation Brigade, dedicated to liberating the remainder of the Golan Heights occupied by Israel since 1967.
‘‘If the Syrian government requests, we are ready to take actions to liberate Golan,’’ Iran’s Tasnim news agency quoted a spokesman as saying.
Iran is also thought to have deployed missiles in Syria capable of reaching deep inside Israeli territory.
While refraining from commenting on the war in Syria, Israel is believed to have carried out unclaimed airstrikes inside Syria targeting suspected Iranian and Hezbollah weapons storage sites and missile depots in recent years. Russia has turned a blind eye to the strikes.
Putin, who has made support for Assad a cornerstone of his policy, would probably be unwilling to go beyond that and support an Israeli incursion.
‘‘Given all this, it is hard to see what Putin could promise to Netanyahu,’’ Frolov said. ‘‘He might, and likely will, promise a lot, but is in no position to deliver.’’