China's nuclear plan has long been based on one principle: a small arsenal, a defensive strategy and saying as little as possible. That attitude is now wearing thin. A new satellite imagery analysis, verified with commercial geospatial data and independent nuclear analysts, has found that China's weapons development programme has had wide-spread construction activity at seven locations Pingtong, Zitong, Lop Nur, Jiuquan, Mianyang, Jinta and Guangyuan. All together, the images suggest more of a mobilization than routine maintenance, and they follow the same path as Beijing's public discourse on disarmament increasingly seems to move out of step with what is actually taking place on the ground.

The best clues come from Pingtong, a remote Chinese village nestled in the mountains of central China which has long been suspected of being the source of the plutonium "pits" that form the core of a warhead. In 2013, a year after Xi Jinping assumed power, ground was broken there, and the site has since been enclosed with new perimeter walls, reinforced gates, a bridge, and what look like underground access points and a residential township with apartment blocks, a sports field and even a bus depot for workers all of which indicate that the site is not merely a temporary build-out, but is in fact the basis for decades of planned activity.

Engineers have built a 600-metre test tube at another site that they think mimics the environment an incoming blast will create on the components of a warhead. A third site, where villages and fields have been cleared to accommodate new laboratories, is reportedly the home of high-powered lasers used to study the behaviour of materials as a nuclear device detonates is undoubtedly a facility with a very clear experimental and forward-looking agenda. “They made a decision under Xi to make a big investment in the nuclear program,” said Renny Babiarz, a geospatial intelligence specialist who reviewed the imagery, meaning Beijing is now more likely to see itself as a power that can stand up to Washington than merely deter it.

The rest of the production chain is completed by the pattern in the other sites. It is believed that Jiuan is home to reactors that produce weapons-grade fissile material. Mianyang is the design and research base, which has been expanded with extra computing power to design new warhead types. Jinta seems to be associated with fuel reprocessing and Guangyuan has expanded to deal with the resulting radioactive waste. The historic nuclear test site at Lop Nur in China's western Xinjiang region has come into particular focus given its connection with a test that the U.S. has branded as being clandestine a claim which has been rejected by Chinese authorities, who have angrily insisted that Washington is responsible for "reactivating a global arms race" rather than the other way around.

All this is not happening in isolation. The Pentagon's latest estimate of China's warhead count stood at more than 600, up from about 200 four years ago, and was expected to reach more than 1,000 by 2030 and continue to increase through 2035. Planners in the United States thought China still possessed only 200 warheads as recently as 2020, and would not be able to muster 400 by the end of the decade. The revision of that estimate is quite significant, and not so much the result of one wrong calculation, but of how rapidly the programme has been moving.

In comparison, the United States and Russia still have approximately 5,000 and 5,500 warheads, respectively, China is still a lot smaller by far. However, what has concerned western capitals is not the number of missiles now deployed, but the rate of closure onto the two nuclear giants by another power that is slow to declare its intentions, and opaque.

As revealing as the engineering is, so are the economics of this build out. China's official defence spending for the current year is above $245 billion, but analysts believe the true figure is between $330 and $450 billion, including off-budget items like research subsidies, veteran benefits and funding for the country's paramilitary forces, which make up nearly 40 per cent of the difference.

The difference is relevant for the valuation of the nuclear expansion in a wide range of risk models by outside observers, such as insurance markets for shipping through the South China Sea or sovereign-risk spreads for Taiwan-bound supply chains. In the United States, Japan, South Korea and Australia, defence contractors and semiconductor-related companies have already started to reassess long-term capital expenditure projects in light of a new security landscape in the Indo-Pacific and nuclear infrastructure investment is now a familiar aspect of that re-evaluation.

The official Chinese stance on the issue has remained unchanged over the years: a “defensive” approach, a “no first use” doctrine and a declaration to maintain military force at “the minimum level needed for the security of the state.” Those words ring hollow against Xi Jinping's public challenge to the world's powers to enshrine nuclear disarmament into their national law.

Those words are at odds with satellite images of permanent worker townships, new reactors, and reprocessing facilities being built in the interior of the country. Also, it should be remembered that the satellite monitoring does not measure confirmed warhead counts or deployment readiness, but rather physical infrastructure, which means that some care needs to be taken when drawing concrete and steel figures into deployment readiness.

But the overall message is hard to ignore. Once minimalist and ambiguous, the nuclear programme is now growing under the gaze of commercial satellites, and at a pace that outside experts liken to the expansion of weapons complexes in the United States, Britain, France and Russia.