The RAF is at the forefront of efforts to respond to increasing Russian hostility, the head of the air force has said.
Speaking at a lecture at the Royal Aeronautical Society, Air Chief Marshal Sir Stephen Hillier also branded Russia's cyberspace actions as "criminal".
In recent days more than 115 Russian diplomats have been expelled across the globe in a diplomatic backlash against the Kremlin following the Novichok nerve agent poisoning of former Russian spy Sergei Skripal and his daughter Yulia earlier this month.
Watch: Air Chief Marshal Hillier tells Forces News it's crucial the RAF stays ahead of the game
On Tuesday, ahead of the centenary of the RAF on Sunday, Air Chief Marshal Hillier said:
"The post-War consensus that has provided the basis for the rules-based international order is being challenged and undermined.
"We must respond, collectively with our NATO and other partners, to counter hostile acts by Russia against our countries, our interests and our values.
"The RAF is in the forefront of that effort."
Watch: Air Chief Marshal Sir Stephen Hillier's lecture to the Royal Aeronautical Society
Air Chief Marshal Hillier said that no one expected a return to the "potential state-based conflict and threats from Russia".
He added of those threats:
"Military grade nerve agent being used for attempted murder on the streets of our country; the reckless and indiscriminate bombing of civilians in Syria.
"The illegal annexation of Crimea, the first time since the Second World War that one sovereign nation has forcibly annexed territory from another in Europe; the criminal activities of the Russian state in cyberspace."
Air Chief Marshal Hillier also revealed that the RAF is the busiest it has been in at least a generation - undertaking the most sustained period of high-intensity war fighting since the Second World War.
With 13 operations in 21 countries on five continents, he said the RAF's work includes fighting Islamic State in Iraq and Syria to defending British skies, as well as Nato operations in Europe and Afghanistan.