SYDNEY, Jan 20 (Reuters) - Britain on Friday warned Russian President Vladimir Putin and Chinese President Xi Jinping that the West would stand together to fight for democracy against dictatorships which it said were more emboldened than at any time since the Cold War. Western leaders say the 21st Century will be defined by a struggle between democracies and rivals such as China and Russia who they say are challenging the post-Cold War consensus militarily, technologically and economically. Speaking in Australia, British Foreign Secretary Liz Truss will say the West must respond together to global threats, deepen ties with democracies in the Indo-Pacific and "face down global aggressors". Global aggressors "are emboldened in a way we haven’t seen since the Cold War," Truss will say in a speech at the Lowy Institute in Sydney. "They seek to export dictatorship as a service around the world. That is why regimes like Belarus, North Korea and Myanmar find their closest allies in Moscow and Beijing." The West, Truss said, should work with allies such as Australia, Israel, India, Japan and Indonesia to "face down global aggressors", especially in the Pacific. "It is time for the free world to stand its ground," Truss The West casts Russia as a dictatorial kleptocracy governed by a mercurial elite that has involved itself in irresponsible escapades such as the 2014 annexation of Crimea, attempts to meddle in U.S. and European elections, and a series of high-profile espionage and assassination attempts abroad. Russian officials say the West is riddled with division, gripped by Russophobia and has no right to lecture Moscow on how to act. China says the West still thinks it can boss around the world in a colonial way and says Beijing will define its own path without meddling from foreign powers. Amid heightened tensions over Ukraine, the West is trying to work out what to do if Russia invades its neighbour. Truss warned Putin to "desist and step back from Ukraine before he makes a massive strategic mistake." Truss will argue that the "Kremlin has not learned the lessons of history" and that "invasion will only lead to a terrible quagmire and loss of life, as we know from the Soviet-Afghan war and conflict in Chechnya." More than 15,000 Soviet troops were lost in Afghanistan from 1979 to 1989, while hundreds of thousands of Afghans perished. The U.S.-led war in Afghanistan from 2001 to 2021 led to over 3,500 deaths among the international military coalition. About 241,000 people have been killed in the Afghanistan and Pakistan war zone since 2001, according to the Costs of War project at Brown University"s Watson Institute.