LONDON: President Vladimir Putin has sent out a challenge to the West, saying he is determined to thwart its plans to remove the Assad regime and is sending generals to Baghdad to co-ordinate policy with Iraq and Iran.
Mr Putin agreed that his dispatch of weapons, including 28 fighter aircraft, armoured personnel carriers and thousands of men to Syria, were aimed at shoring up the embattled regime of President Bashar al-Assad.
The presence of the weaponry at the Bassel al-Assad International Airport was confirmed by aerial photographs taken by a commercial satellite, and analysed by military experts.
Mr Putin said: "It's my deep belief that any actions to the contrary - in order to destroy the legitimate government - will create a situation which you can witness now in the other countries of the region or in other regions, for instance in Libya, where all the state institutions are disintegrated.
"There is no other solution to the Syrian crisis than strengthening the effective government structures and rendering them help in fighting terrorism."
The United States and its Western allies have insisted for four years that under any solution to the Syrian conflict Mr Assad would have to stand down - the demand of the political opposition in exile and rebel groups fighting him.
The British government has shifted its stance - as has the US - to suggest that Mr Assad could stay on in power while a transitional government is negotiated and put in place, to counter arguments that his overthrow would make a bad situation even worse.
But in an interview with the French newspaper Le Monde, Mr Putin said: "Assad must go, he can't be part of Syria's future."
He added: "If we reach a deal on a transition authority and Assad is part of it, then it will be necessary to talk with him in his capacity as an actor in this process."
Mr Putin will meet President Barack Obama on the sidelines of the United Nations General Assembly on Monday. But even that encounter, an attempt to smooth relations and, if possible, thrash out a common position in the need to fight Islamic State of Iraq and Levant (Isil), the one thing to which both powers are committed, was mired in a row.
Josh Earnest, the White House spokesman, said the meeting was agreed in response to "repeated requests from the Russians" with Mr Putin keen to discuss the conflict in Ukraine and the sanctions regime imposed on Russia over its support for anti-Kiev rebels there.
The Kremlin said this was a "distortion", and that the main conversation would focus on Syria.
The Russian move into Syria has changed the calculus of all sides in the conflict. Mr Putin's words make clear he is prepared to help the regime defend itself against the Western-backed rebels, currently on the advance in the north-west, as well as against Isil.
That dashes hopes that further rebel gains could force Mr Assad to the negotiating table. Turkey, which has backed the rebels from the start, has also been trying to persuade the US to support a no-fly zone in the north of the country. That was starting to win backing among politicians in Europe keen to end the flood of refugees to the West. A no-fly zone would enable them to be protected inside Syria.
However, the Americans would be unwilling to risk a confrontation with the Russian air force if it decided to help Syria defend its airspace.
Charles Lister, an analyst at the Washington-based Brookings Institution, who met with leaders of 30 major rebel groups earlier this month, said Mr Putin's move had galvanised them and risked enflaming the conflict further. "They are thirsty for Russian blood," he said. "They are saying, 'Yes, Russia has sophisticated weaponry but this is a second Afghanistan'."
He said the same message was coming from non-Islamist as well as Islamist armed groups, threatening to radicalise the rebels further.
Until now, Russia has presented its support for Mr Assad as part of the war on Isil, encouraging the West to join in. Non-Isil rebels say they are also fighting Isil - the battle is particularly bitter in the north, on the edges of Turkey's proposed no-fly zone - and that attacking them on behalf of Mr Assad would strengthen, not weaken, the militant jihadist movement.
The White House fears Mr Putin's real motive is to take advantage of the crisis to widen its strategic footprint in the Middle East.
The new "co-ordination centre" in Iraq, reported by Fox News, and based on briefings from American officials, would be a step into what had previously been US geopolitical territory.
The report quoted the officials saying Russian officers were "popping up everywhere".
The centre would co-ordinate Russian support for the pro-Iranian Shia militia which do much of the ground fighting against Isil in Iraq. It would be the first Russian presence in Iraq since Soviet times. The US has been reluctant to support these militias directly from the air because of their record for fighting American and British troops in recent years, and their reputation for sectarian thuggery.
General Qassem Suleimani, head of the Iranian al-Quds Force, has reportedly been in Moscow twice in recently.
The Iranian president Hassan Rouhani, visiting New York for the General Assembly, said guardedly:
"I do not see a coalition between Iran and Russia on fighting terrorism in Syria."