WASHINGTON/MOSCOW: U.S. President Barack Obama said Friday that Russia’s escalated military involvement in Syria is an indication that Syrian President Bashar Assad is worried and is turning to Russian advisers for help. Obama said the United States is going to be engaging Russia to say that its support of Assad is “doomed to failure,” Obama said in a town hall with U.S. military service members to mark the anniversary of the Sept. 11, 2001, attacks.

“The strategy that they are pursuing right now, doubling down on Assad, I think is a big mistake,” he said, warning Moscow was “going to have to start getting a little smarter.”

Russia Friday called for military-to-military cooperation with the United States to avert “unintended incidents” as it stages naval exercises off the coast of Syria.

The U.S. is using Syrian air space to lead a campaign of airstrikes against ISIS, and a greater Russian presence raises the prospect of the Cold War superpower foes encountering each other on the battlefield.

In recent days, U.S. officials have described what they say is a buildup of Russian equipment and manpower. In the latest reports, two Western officials and a Russian source told Reuters Moscow is sending advanced SA-22 anti-aircraft missiles Syria. The system would be operated by Russian troops, rather than Syrians, the Western officials said.

Lebanese sources have told Reuters that at least some Russian troops are now engaged in combat operations in support of Assad’s forces. Moscow has declined to comment on those reports.

At a news conference, Foreign Minister Sergey Lavrov said Russia was sending equipment to help Assad fight ISIS. Russian servicemen were in Syria, he said, primarily to help service that equipment and teach Syrian soldiers how to use it.

Russian naval exercises in the eastern Mediterranean were long-planned and in accordance with international law, he said.

A source close to the Russian navy told Reuters a squadron of five Russian ships equipped with guided missiles had set off to conduct maneuvers in Syrian waters.

“They will train to repulse an attack from the air and to defend the coast, which means firing artillery and testing short-range air defense systems,” the source said, adding that the exercise had been agreed with the Syrian government.

Lavrov blamed Washington for cutting off direct military-to-military communication between Russia and NATO after the crisis in Ukraine last year. Such contacts were “important for the avoidance of undesired, unintended incidents”, Lavrov said.

“We are always in favor of military people talking to each other in a professional way. They understand each other very well,” Lavrov said. “If, as [U.S. Secretary of State] John Kerry has said many times, the United States wants those channels frozen, then be our guest.” The dispatch of advanced anti-aircraft missiles like the SA-22, which the two Western officials said were on their way but had not yet arrived, would appear to undermine Moscow’s argument that its sole aim is to help Damascus fight ISIS: The militants and other insurgents possess no aircraft.

French Foreign Minister Laurent Fabius said it was too early to judge what Russia’s motivations were in Syria, but “adding war to war” would not help resolve the conflict.

“If it’s about defending the base in Tartous why not? But if it’s to enter the conflict ...” he said, without finishing the thought.

Diplomats in Moscow say the Kremlin is happy for the West to believe it is building up its military in Syria, calculating that this will give it more bargaining power in any peace talks.

Western and Arab countries have backed demands from the Syrian opposition that Assad must leave power under any negotiated settlement. Assad has refused to go, and all diplomatic efforts at a solution have so far have collapsed.

Assad’s supporters have taken encouragement this week from an apparent shift in tone from some European states.

Britain, one of Assad’s staunchest Western opponents, said that it could accept him remaining in place for a transitional period if it helped resolve the conflict.

France said Monday he must leave power “at some point or another.” Smaller countries went further, with Austria saying Assad must be involved in the fight against ISIS and Spain saying negotiations with him were needed to end the war.

The Syrian pro-government newspaper Al-Watan saw Britain’s position as “a new sign of the changes in Western positions that started with Madrid and Austria.”

Syria and Egypt have reportedly agreed on restoring diplomatic ties severed more than two years ago and on developing security cooperation to confront Islamist extremism, a Lebanese daily reported Friday.

Al-Akhbar reported that Syria’s National Security Bureau chief Ali Mamlouk visited Cairo last month where he met with President Abdel-Fattah al-Sisi and other senior military, intelligence and security officials.

The paper cited unidentified sources who described the visit as “successful,” revealing that the two countries discussed ways to introduce security coordination between them to confront terrorism and political solutions to the 4-year-old conflict in Syria.

An Islamist rebel group stormed Syria’s largest prison Friday, seizing two buildings in the complex near Damascus amid heavy fighting, the Syrian Observatory for Human Rights said.

“Jaish al-Islam entered Adra prison and seized two buildings in the women’s section of the complex,” Observatory head Rami Abdel-Rahman said.

The rebels launched an offensive Wednesday on the regime-held complex, which lies in the Eastern Ghouta suburb of Damascus, capturing a hilltop before seizing part of the facility, he told AFP.

“Most of the prisoners there are activists, political figures and human rights defenders who are against the regime” of Assad, said Abdel Rahman.

At least 5,000 prisoners are being held at the facility, almost twice its capacity of about 3,000 prisoners, he added.

When Jaish al-Islam announced their upcoming offensive, security personnel in the women’s section fled, taking the female detainees with them.