By Philippa Fogarty
Leaders from Russia, China and Central Asian states meet in Shanghai on Thursday for what will be the most high profile meeting to date of the Shanghai Cooperation Organisation.
The SCO has started to attract more international attention
This heightened interest is in part due to the presence of Iranian President Mahmoud Ahmadinejad, who is attending as an observer.
Diplomats will watch for signs China and Russia can persuade Iran to accept an EU and US-backed package of incentives in return for concessions on the nuclear issue.
But it is also the growing status of the SCO, once a little-know regional body, that has attracted attention.
"The SCO is moving at a very rapid speed and having much more of an influence than anticipated," says Andrew Small, director of the UK-based Foreign Policy Centre's Beijing office. "Interest in the diplomatic community has mushroomed."
The grouping initially came into being as the Shanghai Five, which reached a series of agreements in 1996 and 1997 on border issues.
It now comprises China, Russia and the four Central Asian states of Kazakhstan, Kyrgyzstan, Tajikistan and Uzbekistan. Four nations - Iran, Mongolia, India and Pakistan - have observer status.
The Central Asian region can help meet China's energy demands
The grouping seemed to benefit all its members. For China, one of the issues was the energy resources it was competing for to fuel its growing economy. Russia and Central Asia could provide them. China in return could provide a market for trade.
And for Central Asian governments, Russia and China represented support without questions over issues such as human rights.
But as the organisation's scope has widened, it has come to be seen as a way for China and Russia to limit US influence in the strategically important Central Asian region.
"Before 9/11, the idea was to have a fairly loose regional security forum," says Dr Paul Cornish, head of the international security programme at think-tank Chatham House. "The job then was to deal with lingering problems associated with the collapse of the Soviet Union."
"But from 9/11 the emphasis began to shift, simply because the US took more interest in the region in terms of sites for its military bases."
Both Russia and China became increasingly concerned about the presence of the US in their backyard.
In June 2005, the SCO raised the issue publicly, issuing a statement calling for a deadline to be set for the withdrawal of US military bases from Uzbekistan and Kyrgyzstan.
"The US was taken by surprise by the 2005 statement," says Mr Small. Subsequently ordered out of Uzbekistan, the US has since been in negotiations to retain its bases in Kyrgyzstan.
Dr Cornish says that this was when the debate about the SCO came alive: "After the SCO made their statement on wanting the US military out of the region, it began to focus attention on the real purpose of the SCO."
China's Assistant Foreign Minister Li Hui denied on Monday that the SCO targets the US. "We do not go in for military blocs," he told a press conference. "We do not go in for confrontation and we do not target any third country."
Oksana Antonenko, a senior fellow at the International Institute of Strategic Studies, suggests another view.
"I am one of the people that has a positive view of the SCO," she says. "The SCO should be seen in the light of Central Asia moving to regain its Asian identity and seeking to move closer to Asia."
Analysts have played down the idea that the SCO could emerge as a regional rival to the US or as some sort of Asian NATO.
The degree of cooperation that is taking place on the defence side is, however, attracting attention. In August 2003, five SCO countries held anti-terror exercises in China and Kazakhstan, and more drills are due to be held in Russia next year.
But Mr Small does not think it is time for the US to be concerned. "The idea that this would actually turn into a full-scale military alliance is not on the cards at the moment," he said.
Both China and Russia are well aware the alarm such a move would provoke in Washington. While Russia might risk it, China would not, he says.
Dr Cornish agrees. "It is far too early to say that this is a Russo-Chinese version of NATO."
The observer states may be a factor in the organisation's development, says Ms Antonenko.
"None of the observer states are interested in the SCO as a political and military alliance. They are primarily interested in economic cooperation and regional development issues."
She says that while Russia sees the SCO as more of a political and security entity, if the observer states start to play a more active role, the organisation will evolve in a more economic direction.
During Thursday's summit, members will finalise agreements on economic and security cooperation, officials say. Smuggling and drug trafficking are also on the agenda.
Members are also expected to issue a declaration laying out the SCO's path for the future.
Dr Cornish believes this path is not yet clear.
"Having raised the issue with its declaration about the US presence, in my view the SCO hasn't answered the question about what the organisation is supposed to be doing," he says.