The Government remains committed to building parliamentary support for RAF air strikes against Islamic State (IS) in Syria despite Russia's intervention in the conflict, Defence Secretary Michael Fallon has said.
Following talks in London with US defence secretary Ash Carter, Mr Fallon said Russian strikes in support of President Bashar Assad risked making "a grave situation even worse".
However he made clear that ministers would not be deterred from seeking support for a new Commons vote for British warplanes to join the US and other coalition aircraft in attacking IS - also referred to as Isil - in Syria as well as Iraq.
We will continue to build the case for military action in north east Syria where Isil is headquartered, where its command and control is. Russian intervention doesn't change that. We will continue to build the case for intervention in the new parliament.
US Defense Secretary Ash Carter has said Russia's actions in Syria are "risky" and "will only inflame the civil war".
He added that Nato "stood strong" against Russia in Ukraine and this "strengthened posture".
ITV News Correspondent Dan Rivers is at the news conference in London.
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Defence Secretary Michael Fallon has said Russian behaviour "threatens our allies".
He also announced £70m is to be invested in the next five years to drive innovation in new technology for the military.
He is speaking at a press conference in London along with US Defence Secretary Ash Carter.
Mr Fallon said: "Aggressive Russian behaviour continues threatening our allies in Europe."
ITV News Correspondent Dan Rivers is at the news conference.
Fallon: aggressive Russian behaviour continues threatening our allies in Europe.
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Russia will pay the price for launching air strikes to prop up the Assad regime, the US defence secretary has warned.Read the full story ›
British troops are to be deployed to the Baltics as part of a long-term Nato mission to deter Russian aggression.
Defence Secretary Michael Fallon said a "small number" of soldiers would be stationed there to "watch over our allies on the eastern borders".
RAF Typhoon fighters are already in the region as part of the Baltic Air Policing detachment and have been called into action in recent months.
In June, Typhoons were scrambled from Amari Air base in Estonia to intercept and shadow two Russian military aircraft over the Baltic Sea.
Fallon said: "This is part of our more persistent presence on the eastern side of Nato to respond to any further provocation and aggression."
Russia is making a very serious situation in Syria much more dangerous, the Defence Secretary has said.
Michael Fallon said if Russia wanted to help the best thing they could do is use their influence to stop President Assad from bombing his own civilians.
He added they must also stop using unguided missiles in Syria.
The Russian Ministry of Defence has posted a video showing its military forces firing rockets off the deck of a warship in the Caspian Sea.
According to confirmation by the country's defence minister Sergei Shoigu four of Russia's military warships targeted Islamic State targets in Syria with 26 missile strikes as part of its pre-emptive operation against terrorism in the Middle East.
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Russia has been carrying out air strikes in Syria at the request of Syrian president Bashar Al Assad but concerns have been raised about who is really being targeted,
Earlier this week Nato told Russia to stop its attacks on civilians and Syrian rebels and concentrate on fighting Islamic State.
Today's rocket attack follows the first reported major co-ordinated assault on Syrian rebels by Syrian forces on the ground and Russian military in the air.
Russian President Vladimir Putin has confirmed that his military's warships, based in the Caspian Sea, have launched rockets on Islamic State.
According to local news agency RIA a total of 26 rockets were launched from four ships.
The head of the Iraqi parliament's Security and Defence Committee has said Iraq is considering asking Russia to carry out air strikes against Islamic State on its soil.
Hakim al-Zamili told Reuters that depending on the Russians success in Syria they may be called in for help.
He said: "We might be forced to ask Russia to launch air strikes in Iraq soon.
"I think in the upcoming few days or weeks Iraq will be forced to ask Russia to launch air strikes and that depends on their success in Syria."