German Chancellor Angela Merkel said Thursday that Syrian President Bashar Assad must be involved in any peace talks that could end the Middle Eastern country’s four-year conflict, according to Agence France-Presse (AFP). Merkel’s comments come amid growing tensions in Syria and Russia's increased military presence in the country, giving rise to concerns over Moscow’s moves to support Assad.

"We have to speak with many actors, this includes Assad, but others as well," Merkel told a press conference after a European Union summit on the refugee crisis sparked by the Syrian war.

"Not only with the United States of America, Russia, but with important regional partners, Iran, and Sunni countries such as Saudi Arabia,” Merkel reportedly added.

Western powers, which were insisting on Assad's departure, are reportedly not giving it as much importance now in a bid to end the war.

U.S. Secretary of State John Kerry said Saturday that while Assad must step down, settlement over the issue could be delayed to end the country's civil war. British Foreign Secretary Philip Hammond’s comments on the war in Syria and Assad also echoed Kerry’s statement.

However, French President Francois Hollande, whose country is set to launch airstrikes against the Islamic State group militants in Syria, insisted Thursday that there could be no place for Assad.

"There can be no transition without his departure," Hollande said after the summit, according to AFP. "The future of Syria will not pass through Bashar Assad."

The U.S. and Russia began military talks over the Syrian conflict last week as Moscow beefed up its military presence in the war-torn country. 

On Wednesday, Bloomberg reported, citing sources, that Russian President Vladimir Putin is preparing for unilateral airstrikes against ISIS if the U.S. rejects his proposal to join forces.

"They are not going to sit around and defend the airfield or maybe even the province of Latakia,” analyst Jeffrey White of the Washington Institute for Near East Policy said earlier this week, according to AFP. "This kind of aircraft suggests that the Russians intend to exert their combat power outside of Latakia in an offensive role.”

John Kirby, a spokesman for the U.S. State Department, had also expressed concerns over Russia’s move, saying that it’s unclear whether Moscow aims to battle ISIS in Syria or "prop up the Assad regime."

Iran's Deputy Foreign Minister Hossein Amir Abdollahian said Moscow and Tehran would work together to help end the crisis in Syria, Reuters reported, citing RIA news agency.

"Tehran and Moscow intend to use all possibilities and potential to help Syria come out of this crisis," he reportedly said at a news conference in Moscow, adding that his country had no troops or military advisers in Syria or Yemen.

But, British Defense Secretary Michael Fallon said Tuesday that there have been no discussions with Russia about any military action in Syria, Reuters reported.