in a dire struggle over tech.

And some analysts say it's likely

that tensions could escalate from here, jeopardising

the business dealings of both American companies

and their Chinese counterparts.

The tech war is part of the broader US-China trade war that

started more than a year ago.

But while the trade war is being fought

with tit-for-tat tariffs, the tech war

is being waged with direct action against companies.

America has blacklisted more than 140 Chinese companies,

severely limiting their access to US-made components

that they rely on.

This has already thrown several Chinese companies,

such as Huawei, into crisis.

But China is fighting back.

It has not publicly ordered a backlash

against American corporations in China,

but some US companies are now facing stiff headwinds.

Chuck Robbins, chief executive of Cisco, the US networking

equipment maker, says Chinese state-owned companies are

blocking it from deals and that Cisco

is being uninvited to bid for some Chinese contracts.

If this treatment goes mainstream,

US companies have a lot to lose.

This chart shows how US companies operating in China

sell nine times more to Chinese customers

than Chinese companies operating in the US sell to Americans.

Another giant US corporation, the chip maker Qualcomm,

also reported weakness in its China business.

The company, which gets 65 per cent of its revenue

from sales in China, warned that earnings are on track

to fall to a seven-year low.

America's aim in confronting China over technology

is to punish specific companies, such as Huawei,

for alleged wrongdoings.

But this is feeding into a bigger and bleaker picture.

The rivalry between the US and China

is reversing nearly 40 years of economic engagement

between the world's two superpowers

and ushering in an era of decoupling.