Accelerating Chinese investment in Afghanistan is focusing attention on the question of China's future role in that country.
This week a Chinese company won the right to develop certain Afghan oilfields. This is not the first Chinese resource play in Afghanistan, nor will it be the last.
The common perception has been that while investing vigorously, China will not engage politically or militarily in Afghanistan, for fear of stirring separatist sentiments in the volatile Xinjiang region bordering Afghanistan, among other reasons.
This idea will seem less plausible when the US troop withdrawal starts in 2014. A Chinese military and political engagement in Afghanistan - including greater efforts against insurgents in Muslim-dominated Xinjiang - would also serve China's long-term strategic aims.
China has reportedly shown interest in setting up military bases in Pakistan's insurgency-hit northwestern tribal areas, along the border with Afghanistan.
Chinese authorities believe that East Turkestan Islamic Movement (ETIM), a terrorist group with bases in Pakistan, has been orchestrating attacks in Xinjiang including one which killed 19 people in the city of Kashgar last July. The Chinese believe ETIM terrorists acquired explosives skills, and firearms, in camps in Pakistan.
China's military presence in tribal areas along the Afghanistan border would be focused on countering extremist elements fuelling unrest in Xinjiang. A politically stable and economically developed Xinjiang is essential to Chinese plans for regional trade and energy corridors in the region.
China has also significant economic presence in Balochistan, the southwestern Pakistani province bordering Afghanistan.
Already the biggest foreign investor in the port city of Gwadar, China reportedly plans to establish a naval base there. Gwadar, Balochistan's winter capital, is strategically located close to the Strait of Hormuz.
A naval base there, plus military bases in north-west Pakistan, would help China to assume the role of regional policeman.
For now, China's economic presence in Afghanistan enjoys the security shield of the US military. When US troops leave, China will have only two options - to leave Afghanistan or to find a way to defend their huge Afghan investments, such as the Aynak copper project, from Taliban insurgents.
In the Aynak deal, China must remain for 30 years for mining operations. It has also pledged to build rail and road connections to transport minerals to China.
Last year, the Afghan authorities and the State-owned Metallurgical Corp of China (MCC) signed a $7 billion (Dh25.7 bn) deal to build a rail line from the border with Pakistan up through Kabul and the Aynak copper deposit south of Kabul and then up to the Uzbek border.
What will be the fate of this project after the withdrawal of US troops? Under what conditions is it logical for China to make more huge investments in Afghanistan?
It is hard to believe that resource-hungry China will just walk away from these projects. And to defend its projects, China is unlikely to rely solely on Afghan forces, which are still not fully reliable.
It is highly likely, then, that China will come to replace the US in fighting the Taliban in Afghanistan. Pakistan would continue to play a front line role against Islamist extremists as China's strategic ally, while the Shanghai Cooperation Organization (SCO) could assume the role now played by Nato. In all this Pakistan will be China's vital strategic partner.
As an alternative to the US, Beijing can extend much-needed financial assistance to Pakistan.
Pakistan has been the major supply route for US and Nato missions to Afghanistan. China, which shares a small, mountainous border with Afghanistan, may open a major route for overland transit of military supplies.
The route could follow existing railway routes within China before crossing into Kazakhstan, where it could be linked up with supply lines that traverse Uzbekistan and Tajikistan. All this would permit development of adequate transit links into Afghanistan. Along with ocean links to Pakistan, this could provide China with sustainable ways to get military supplies into Afghanistan.
On November 26, a Nato attack on a Pakistani border post killed 26 Pakistani soldiers. In retaliation, Islamabad has threatened to halt its efforts to persuade the Afghan Taliban to negotiate.
But that incident merely demonstrated an emerging geopolitical reality: a strategic consensus between China and Pakistan threatens to scuttle US prospects of ending the war in Afghanistan.
Islamabad is prepared for strategic cooperation with China, in a bid to cut the US out of Afghanistan. And China, ready and willing to exploit Pakistan's volatile relationship with the US, has the resources for both economic and military investment.
Syed Fazl-e-Haider (www.syedfazlehaider.com), a development analyst in Pakistan, has written many books, including The Economic Development of Balochistan.