JERUSALEM — It was not the deal he was hoping for, but Prime Minister Benjamin Netanyahu of Israel left Moscow on Thursday saying he had won an important commitment from President Vladimir V. Putin.
Israel, he said, did not object to President Bashar al-Assad’s regaining control over all of Syria, a vital Russian objective, and Russia had pushed Iranian and allied Shiite forces “tens of kilometers” away from the Israeli border.
Mr. Netanyahu’s suggestion of progress in talks with Mr. Putin came at a crucial moment: Syrian forces backed by Russia and Iran are laying siege to a rebel-controlled pocket of southwestern Syria, sending hundreds of thousands of people fleeing toward Jordanian and Israeli territory.
With Syrian government forces raising the national flag on Thursday over Dara’a, birthplace of the revolt against Mr. Assad, the endgame of the Syrian civil war seemed to be fast approaching. And with it, time could be running out for Israel to dislodge Iran from Syria by diplomatic means.
Adding to the urgency is a summit meeting on Monday between Mr. Putin and President Trump in Helsinki, where Iran and Syria are expected to be on the agenda. Mr. Netanyahu moved up his meeting in Moscow by several days to make a last pitch to Mr. Putin before the meeting.
But a commitment to keep Iranian forces tens of kilometers from Israel was a far cry from ejecting them completely from Syria, which Mr. Netanyahu has been lobbying Mr. Putin to do. And even that commitment was not confirmed by Russian officials.
“We are aware of your concerns,” Mr. Putin told Mr. Netanyahu, the Kremlin said. Then the two leaders met privately.
On Thursday, Mr. Putin met with a top Iranian foreign policy official, Ali Akbar Velayati, leading to much speculation in Israel and abroad, but neither country provided public details of that discussion.
Israel has largely stayed out of Syria’s civil war but has carried on a shadow war in Syria with Iran, which has taken advantage of the chaos to build a military infrastructure in Syria.
But it is unclear how much leverage Israel has to press its anti-Iran agenda diplomatically.
Israel has little stomach for Mr. Assad’s regaining full control of Syria: One senior government official likened it to “swallowing a poisoned frog,” given that Mr. Assad had gassed his own people.
So a willingness to accept Mr. Assad’s resumption of control over all of Syria is no small concession, said Amos Yadlin, a former chief of Israeli military intelligence who now heads the Institute for National Security Studies in Tel Aviv.
“Nobody can these days destabilize the Assad regime,” he said. “The only one who can do it is Israel. And the Russians know that very well. So to get a commitment from Israel not to destabilize Syria is something that Russia will value very much.”
Mr. Assad, while an avowed enemy of Israel, has taken pains to avoid a battle with Israel and has maintained the truce that has held since 1974.
“We haven’t had a problem with the Assad regime,” Mr. Netanyahu said, according to the Israeli newspaper Haaretz. “For 40 years, not a single bullet was fired on the Golan Heights.”
But Israel’s threats — to interfere with Mr. Assad’s efforts to recapture southwestern Syria, or to retaliate against Iranian forces’ entrenchment in Syria with strikes against Iranian and Syrian government positions — are getting old, said Ofer Zalzberg, an analyst at International Crisis Group: “Moscow tolerated it for awhile, but they’re unhappy with this as a long-term pattern,” he said.
Even if it agreed with the Israeli position, there are limits to what Russia can do. Russia could be expected to do little more than “communicating with Iran and asking them politely” to move farther from the Israeli border, and its promises would likely be both short-lived and difficult to enforce, Mr. Zalzberg said. “I don’t see Russia as likely to deploy a sizable contingent of its military police in the southwest with some kind of endless duration,” he said.
Andrei Kortunov, head of the Russian International Affairs Council, a research group that advises the Kremlin, said that even if Mr. Putin were to agree to try to oust the Iranians from Syria, “Iran also needs to sign up to this too.”
Pressure can only accomplish so much, Mr. Kortunov said. And besides, he said, “You can move the Iranian forces by 50 or 80 or even 100 kilometers away from the Golan Heights, but if the infrastructure remains there and if this territory is still controlled by Damascus, then it won’t be difficult to bring the Iranian forces back.”
Syrian forces moved a step closer to regaining control of the border region on Thursday, taking over the neighborhood in Dara’a where the uprising that set off the country’s civil war began in 2011. Dara’a is the main city in one of the last remaining rebel-held areas of the country.
Antigovernment activists and a conflict monitor said that the government had not yet driven rebels from the entire city, but that talks were taking place over a surrender deal that would leave the whole city in government hands. As in previous such deals, the rebels were expected to be given the option to disarm and accept the government’s rule or be bussed to rebel-held territory in the northeast.
Seven years into the war, Mr. Assad has consolidated his control over the country’s center and its main population centers, although large amounts of territory remain out of his control. After the battle for Dara’a, the fighting is expected to continue to the west, toward the frontier with the Israeli-occupied Golan Heights, pitting the government and its allies against other rebels and a jihadist group connected to the Islamic State.
While it is unclear how Mr. Assad will bring these areas back under his control, few doubt that he will remain the president of Syria. With that outcome a foregone conclusion, the diplomatic battle has turned to what that Syria will look like.
David M. Halbfinger reported from Jerusalem, and Ben Hubbard from Beirut. Ivan Nechepurenko and Sophia Kishkovsky contributed reporting from Moscow, and Ronen Bergman from Tel Aviv.