Russia and China staged their biggest joint exercises on Friday but denied this show of military prowess could lead to the formation of a counterweight to Nato.
The war games were staged under the flag of the Shanghai Cooperation Organisation (SCO), a regional grouping that includes Russia, China and four Central Asian states.
Russian president Vladimir Putin, who watched the war games with Chinese president Hu Jintao, dismissed comparisons with the western North Atlantic Treaty Organisation (Nato).
"Today's exercises are another step towards strengthening the relations between our countries, a step towards strengthening international peace and security, and first and foremost, the security of our peoples," Mr Putin said.
Fighter jets swooped overhead, commandos jumped from helicopters on to rooftops and the boom of artillery shells shook the firing range in Russia's Ural mountains as two of the largest armies in the world were put through their paces.
The exercises take place against a backdrop of mounting rivalry between the West, and Russia and China for influence over Central Asia, a strategic region that has huge oil, gas and mineral resources.
Russia's growing assertiveness is also causing jitters in the West. Putin announced at the firing range that Russia was resuming Soviet-era sorties by its strategic bomber aircraft near NATO airspace.
Commanders said the aim of the exercises - involving 7,500 troops from SCO member states -was to practise joint operations for putting down a militant uprising.
Moscow has been fighting a separatist insurgency in its southern Chechnya region while China says it is fighting Uighur Muslim rebels in its westerly province.
"I am convinced that the current exercise will definitely serve to stimulate the SCO to play a bigger role in the struggle against terrorism in the region," Mr Hu said.
Asked by a reporter if the SCO was turning into a counter-balance to Nato, Mr Putin said: "That is not the case."
"The military aspect is not dominant and not the main thing ... The SCO is an organisation that deals with questions of a political character and an economic character ... and the economic aspects are at the forefront," he said.
Building the alliance may be hindered by the ambiguous relations between Russia and China.
Moscow wants to supply energy to China's booming economy and sell its weapons to its military, but is also wary of Beijing's growing economic and military might.