China
Major religions: Buddhism, Christianity, Islam, Taoism
China has said it will join the fight against terrorism. But it is unlikely to let United States forces use the narrow strip of its territory that borders Afghanistan.
Tajikistan
Major religion: Islam
Tajikistan is the only country in the region which accepts a Russian military presence. It says it is ready to discuss cooperation with the US, but as its security and economy depend heavily on Russia, it will probably do whatever the Russians tell it to do. Neighbours have accused it of allowing Islamist rebels to operate training camps but the government strongly denies this.
Uzbekistan
Major religion: Islam
Uzbekistan has said it might discuss allowing the US to use its bases and airspace to attack extremist groups in Afghanistan, but that it has not made a final decision. It is unlikely to do so without Russian approval. Air bases at Tashkent and Termez could be useful to the US.
Turkmenistan
Major religion: Islam
It has large natural gas and oil reserves but remains impoverished because it has no means of exporting them as a result of disputes with neighbours. Turkmenistan has remained silent on the possibility of assisting the US. It appears reluctant to become involved and it is unlikely to do so without approval from the Russians, on whom it is economically dependent.
Iran
Major religion: Shi’a Islam
Iran shares a 896km border with Afghanistan. Last week Iran said it was closing the border, partly to avoid a flood of refugees but also to close a possible escape route for those close to Osama bin Laden. Iran opposes the Taliban but is also hostile to the US. But the supreme leader, Ayatollah Ali Khamenei, appeared to quash US hopes on Thursday when he said Iran would not support any attack on Afghanistan that could lead to a human catastrophe.