NEW YORK: Russia’s President Vladimir Putin Sunday launched a new coalition to battle ISIS in Syria as he prepared to confront U.S. rival Barack Obama at the United Nations. The dramatic diplomatic gambit underlined how Russia has seized the initiative on Syria, as U.S. Secretary of State John Kerry met his counterpart Sergey Lavrov to express his concerns.

Putin and Obama are to make dueling speeches Monday before the United Nations General Assembly in New York, and will come face-to-face in a private meeting at a time of high drama.

But even as the diplomatic playing pieces are coming into place, the facts on the ground are shifting, with Iraq confirming that it is to share intelligence with Russia, Iran and Syria.

The United States has built its own coalition of mainly Sunni Arab and Western countries to fight the ISIS in Iraq and Syria, but Russia is taking another course. As Kerry began talks with Lavrov on the sidelines of the U.N. meeting, he urged Russia not to go it alone.

“I think the critical thing is that all of the efforts need to be coordinated. This is not yet coordinated,” he said.

“I think we have concerns about how we are going to go forward. That is precisely what we are meeting on to talk about now.”

Washington has demanded that Syrian strongman Bashar Assad step down, but Putin’s rival alliance with Shiite-led states will instead shore up the beleaguered government in Damascus.

Western powers say Assad’s military is responsible for the vast majority of the 240,000 deaths in the four-year war, but Putin said there is only “one legitimate conventional army” in Syria.

“We have proposed to cooperate with the countries in the region. We are trying to establish some kind of coordinated framework,” Putin said in an interview with CBS News “60 Minutes.”

“We would welcome a common platform for collective action against the terrorists,” he said, in excerpts released Sunday.

Iranian President Hassan Rouhani said he saw a widespread acceptance among major powers that Syrian leader Assad should stay in office.

“I think today everyone has accepted that President Assad must remain so that we can combat the terrorists,” Rouhani told CNN.

“In Syria, when our first objective is to drive out terrorists and combating terrorists to defeat them, we have no solution other than to strengthen the central authority and the central government of that country as a central seat of power,” said Rouhani, who is also visiting New York for the U.N. General Assembly.

British Prime Minister David Cameron called for discussions on how to bring about political transition in Syria.

Britain has stressed that Assad would not necessarily have to go immediately as part of a peace deal.

“Assad can’t be part of Syria’s future. He has butchered his own people. He has helped create this conflict and this migration crisis. He is one of the great recruiting sergeants for ISIL [ISIS],” Cameron told reporters on the flight to New York, according to the Press Association.

“He can’t play a part in the future of Syria and that position hasn’t changed,” he added.

“Obviously conversations about how we bring about transition are very important and that’s what we need to see greater emphasis on.”

Cameron is expected to drop his opposition to Assad playing a role in any transitional government, according to broadcaster the BBC.

French President Francois Hollande, announcing France’s first airstrikes against ISIS in Syria, said that “France is talking with everyone and excluding no one,” Hollande said at the U.N. While “all concerned parties” must be included, he also stressed that “the future of Syria cannot [include President] Bashar Assad.”

Stressing the need to work with Assad to defeat the militant threat, Putin mocked the $500 million U.S. effort to train Syrian anti-ISIS fighters.

“As few as four or five people actually carry weapons, the rest of them have deserted with the American weapons to join ISIS,” he said.

The Pentagon has confirmed that one group of U.S.-trained rebels surrendered some of their equipment to an Al-Qaeda-linked militia, apparently in return for safe passage.

Washington and its allies counter that Assad triggered the civil war that has given militant factions room to grow, and continues to make a political settlement impossible.

U.S. Ambassador to the United Nations Samantha Power told ABC News: “We haven’t seen a dictator like him in a very long time.

“The other challenge is he hasn’t been at all effective fighting ISIL. In fact, the presence of Assad has attracted foreign terrorist fighters,” she argued, using another name for ISIS.

Washington and its allies refuse to put boots on the ground in Syria, despite the extraordinary chaos after four years of intense bloodshed, but Russia is ramping up its presence.

Moscow already has a powerful military detachment on a Syrian airbase in government-held territory, equipped with warplanes and tanks, and will now work more closely with neighboring Iraq.

Saad al-Hadithi, a spokesman for Iraqi Prime Minister Haider al-Abadi’s office, told AFP that officers from Russia, Iran, Syria and Iraq would work together in Baghdad.

“It’s a committee coordinating between the four countries, with representatives of each country, in the field of military intelligence,” he said.

Iraq will continue to work with the U.S.-led anti-ISIS coalition, but the new Russian presence in the capital captured by U.S. forces in 2003 and occupied for a decade sends a powerful signal.

Obama and Kerry are hoping to use the week of the U.N. General Assembly to strengthen the resolve of their own coalition and build momentum for the fight against militant violence.

The U.S. president will address the crisis in his own address and hold a parallel summit on violent extremism, while Kerry and U.S. allies rally support for the anti-ISIS battle.

But all eyes will now be on Obama’s faceoff with Putin, who suggested that Washington’s support for “moderate” Sunni rebels in Syria was illegal and a source of much of the violence.