Last October Ken McCallum, the head of the UK’s domestic intelligence agency MI5, spelled out the dangers posed by Beijing in no uncertain terms.

‘Do Chinese state actors present a UK national security threat? The answer is of course, yes they do, every day,’ he told journalists in a rare public appearance.

Which makes it all the more stupefying that, as the Daily Mail reported yesterday, Britain’s armed forces are using Chinese-made 3D printers to manufacture critical weaponry, including drones.

In fact, as I can reveal today, the problem goes far beyond small-scale armaments. The truth is that Britain’s reliance on China is so dangerously far-reaching that the only way we can rearm – in the unlikely event that this Labour Government ever comes up with the budget for us to do so – is if Beijing lets us.

Thanks to China’s stranglehold on much of the tech and components we use in the manufacture of our military equipment, we are reliant on the goodwill of a communist one-party state for the firepower to keep us safe in an increasingly dangerous world.

The worst case scenario is that secret elements installed in Chinese equipment – software or hardware – will allow Beijing to turn our weapons on and off at will.

The ‘hijacking’ of weapons is now science fact, not science fiction. We’ve seen examples of it on the battlefield, with the Russians employing a new form of electronic warfare to ‘capture’ Ukrainian drones in mid-air and redirect them towards the Baltic States.

Imagine if British drones were manipulated in such a way that they gave away their positions at the height of battle. Worse still, imagine if missiles fired from ships or planes reversed course to destroy the very vessels and aircraft that launched them.

That is the very modern danger we face if we don’t closely monitor the composition of our defence supply chains. But thanks to the astonishing complacency of the Ministry of Defence and Whitehall, we cannot say with any certainty how vulnerable we are.

Take the printers issue. The Government doesn’t know how many Chinese-made 3D printers it has installed, perhaps because they are such low-cost items they may well have fallen under the threshold to be audited.

Yet they could act as vital sources of intelligence to what is clearly an unfriendly foreign power. The House of Lords was recently told that 90 per cent of data collected by Chinese-made cars is beamed back to servers in China. Who’s to say that 3D printers – or other weaponry riddled with Chinese components – won’t do the same?

Part of the problem is that just ten out of the major two dozen defence suppliers are domiciled here, so monitoring extended global supply chains is difficult. In that Lords debate it also emerged that 85 per cent of our military drone components come from China. And they are by no means the only weaponry bearing a metaphorical ‘Made in China’ sticker.

Beijing’s encroachment into the high-tech sectors of the West’s defence industry is part of a well thought out plan that dates back to the introduction of its ‘Made in China 2025’ policy. This signalled a pivot away from its strategy of being the world’s go-to manufacturer of low-cost goods to attaining global dominance in ten high-tech sectors, including robotics, aerospace and semiconductors.

China went about this with its customary ruthlessness: stealing tech from competitors, undercutting them on price and forcing them out of business. Its ultimate purpose is to first match the West’s military might and then surpass it.

There are far too few MPs and ministers who understand the scope of China’s ambition or grasp the implications of it ever being achieved. Instead, we seek to ingratiate ourselves with China’s leadership – you could call it Operation Kowtow – in the forlorn hope of an economic El dorado.

As ever, the US has been more open about the problems posed by a sabre-rattling China than our own government. Last summer, its Government Accountability Office warned of a ‘dangerously high dependency’ on China when it came to critical American military systems.

Investigations into its defence contractors revealed hundreds of Chinese suppliers. Some 41 per cent of US weapon systems contained Chinese semiconductors, for example. That figure rose to 91 per cent of naval weapons.

This raises uncomfortable questions about the security of Taiwan, which lives in constant fear of a Chinese takeover. If Beijing were to restrict supplies of components to Washington in the build-up to an invasion, would the US be in any position to resist it?

Shockingly, production of its cutting edge F-35 jet fighters once had to be halted for months due to the discovery of Chinese components. Submarine production is another area of concern because the US lacks the ability to produce vital components, such as titanium castings.

Meanwhile, the West’s dependence on Chinese semiconductors is stark. F-18 jets each have 5,000 Chinese semiconductors, while Arleigh Burke-class destroyers have 6,000. Is this a problem? Well, let me give you an example of how electronic deception in warfare is being conducted.

During the original 2014 Russian invasion of Ukraine, the Russians cleverly seeded malware on an artillery app used by Ukrainian gunners.

Every time they used it, Ukrainian gunners gave away their position. So instead of the app being used to target and kill Russians, Ukrainians unwittingly put a target on their own backs every time they used it. There is every reason to believe China might now, or in the near future, use its own semiconductors in UK, US or Nato ships and planes to send location information back to China.

The stark reality is that for the UK, the military ‘superiority’ we have taken for granted – and which we have complacently run down – is increasingly dependent on China, a country we may have to confront in the years ahead.

We need to understand the deep threat to us from hostile nations in our increasingly complex military supply chain. Where we can’t onshore, we need to ‘friendshore’, ensuring our supplies are safe and encouraging our allies to do likewise.

Western nations are beginning to learn. The US drone dominance programme, fast trying to understand the lessons of the Ukraine war, is demanding zero Chinese components in US production lines.

In the UK, we are making tentative moves, too. But too often, it’s two steps forward, one step back. While we now have the National Security And Investment Act, enabling the Government to make it easier to block takeovers on national security grounds, it was made deliberately weak, with defence considerations given secondary billing.

Last year the Cabinet Office ordered an end to using Chinese-made surveillance equipment while MoD officials restricted vehicles containing Chinese-made sensors, radars and microphones from key military sites, citing fears they could transmit intelligence back to Beijing. But this is just the start.

The true purpose of a country’s military capability is to deter war. But to deter war, deterrence must be convincing. If our enemies know that not only are we poorly armed but that they can turn off our weapons – or potentially even train them on ourselves – we will be sleepwalking to a 21st century catastrophe of Pearl Harbor proportions from which we will not recover.

Dr Bob Seely MBE is the author of The New Total War