The army camp will be built in Afghanistan's remote and mountainous Wakhan Corridor, where witnesses have reported seeing Chinese and Afghan troops on joint patrols.
The freezing, barren panhandle of land -- bordering China's tense Xinjiang region -- is so cut off from the rest of Afghanistan that many inhabitants are unaware of the Afghan conflict, scraping out harsh but peaceful lives.
However they retain strong links with neighbours in Xinjiang, and with so few travellers in the region local interest in the Chinese visitors has been high, residents told AFP on a recent visit there.
The Chinese are pouring billions of dollars into infrastructure in South Asia. With Afghanistan's potential to destabilise the region, analysts said any moves there would be viewed through the prism of security.
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Beijing fears that exiled Uighur members of the East Turkestan Islamic Movement (ETIM) are passing through the Wakhan into Xinjiang to carry out attacks.
It also worries that Islamic State group militants fleeing Iraq and Syria could cross Central Asia and Xinjiang to reach Afghanistan, or use the Wakhan to enter China, analysts say.
"We are going to build it (the base) but the Chinese government has committed to help the division financially, provide equipment and train the Afghan soldiers," he told AFP recently.
A senior Chinese embassy official in Kabul would only say Beijing is involved in "capacity-building" in Afghanistan.
NATO's US-led Resolute Support mission in Afghanistan declined to comment. But US officials have previously welcomed China's role in Afghanistan, noting they share the same security concerns.
Members of the Kyrgyz ethnic minority in Wakhan told AFP in October they had been seeing Chinese and Afghan military patrols for months.
The Afghan army arrived days earlier "and told us that the Chinese army would be coming here", he said, adding: "We were strictly told not to go near them or talk to them and not to take any photos."
Rashid's account was confirmed by other Kyrgyz, including another chief Jo Boi, who said the Chinese military spent almost a year in Wakhan before leaving in March 2017.
Both Chinese and Afghan officials deny the claims, with China's defence ministry telling AFP that the "Chinese army is not engaged in any military operation in the Wakhan Corridor".
"They are very good people, very kind," he told AFP.
After their March visit, he said, they returned in June for roughly a month. "Since then they come every month... to distribute food."
China fears militancy could threaten its growing economic interests in the region, Ahmad Bilal Khalil, a researcher at the Kabul-based Center for Strategic and Regional Studies, told AFP.
"They need to have a secure Afghanistan," he said, estimating Beijing had provided Kabul with more than $70 million in military aid in the past three years.
"The anti-terrorism motivation is an important one but it's not as important as the bigger move to boost the CPEC," said Willy Lam, a political analyst in Hong Kong.