Russia and China dominate a regional grouping, the Shanghai Cooperation Organisation (SCO), that after a very low-key start has begun to show some strength.
"The SCO has emerged, in Moscow's eyes, as a balance to the US influence in the region," said Andrei Pyontkovsky, an analyst for the Centre of Strategic Studies think-tank.
The organisation was created in 1996 to help solve post-Soviet border problems, grouping the giant neighbours with four former Moscow-run states, Tajikistan, Uzbekistan, Kazakhstan and Kyrgyzstan.
A coup earlier this year in impoverished Kyrgyzstan, which followed popular revolts the previous two years in former Soviet states Georgia and Ukraine, had alarmed the predominantly Muslim region of hardline governments.
Russia's ambitions for the organisation received a lift this month when it held its first military exercises with China, which was the only time their two armies have cooperated on any significant scale since the Korean war in the 1950s.
Growing military cooperation
The manoeuvres in China's Shandong peninsula, involving about 10,000 troops along with strategic bombers, were officially aimed at quelling ethnic conflicts and resisting any interference by a "third force" - an apparent reference to the US.
For the moment Beijing, focused on Taiwan, does not have enough practical interests in Central Asia to challenge the United States, which remains its main trading partner"
independent defence analyst
For China, political observers said, a demonstration of growing military cooperation with Russia was a chance to send a potent message to its arch-foe Taiwan.
But Russian officials made no attempt to hide their view that last week's Peace Mission 2005 exercises were part of what they want to be a new role for the SCO.
"In principle, the SCO is not a military organisation," Interfax news agency quoted an unnamed top Russian military official as saying after the exercises. "But as time goes by, it is increasingly adopting new military elements."
The head of the grouping's security body, Vyacheslav Kasymov, added: "Peace Mission 2005 demonstrates the potential of military cooperation in fighting terrorism ... on the whole territory of the SCO."
Averting velvet revolutions
Instability in Central Asia, with its long and porous borders with Russia, has been a problem for Moscow since the Soviet Union collapsed in late 1991.
Initially, it was the fighting in Afghanistan which most worried Moscow.
In 2001, Russia backed the US-led invasion of Afghanistan. The Kremlin even gave its blessing to Uzbekistan and Kyrgyzstan to host US military bases.
But that view started to sour as Moscow grew suspicious the West was encouraging people-power revolts in Central Asia.
Uzbekistan, with the open support of its SCO partners, has now told US troops to leave.
The change of policy follows heavy Western criticism of the Tashkent government after its troops killed more than 500 protesters in the eastern town of Andijan in May.
Kazakhstan's leaders, too, look increasingly worried about possible opposition protests during the presidential election in December.
Uzbekistan was criticised after its
troops killed 500 protesters in May
The SCO is also urging Washington to name a date for withdrawing its troops from Kyrgyzstan.
But most analysts doubt that China will, for the moment, be a key military player in the region.
"For the moment Beijing, focused on Taiwan, does not have enough practical interests in Central Asia to challenge the United States, which remains its main trading partner," said Pavel Felgengauer, a leading independent defence analyst.
Isolationist Turkmenistan, the other former Soviet republic in the region, has declared itself neutral and is not part of any regional groupings.