US hypersonic missile research could end up antagonising China and Russia, despite hopes that it could help defuse tensions over renewal of Washington's nuclear intercontinental ballistic missile (ICBM) arsenal.

The Prompt Global Strike (PGS) programme aims to develop a hypersonic, precision-guided conventional weapon that can deploy anywhere in the world within one hour.

“Initially we might think that [hypersonic] is the silver bullet,” Mark Hilborne, lecturer at the defence studies department of King’s College London, told the Royal Aeronautical Society’s air power conference. “But these weapons might undermine strategic agreements between nuclear states.”

Hilborne says that both China and Russia are developing their own air-launched hypersonic weapons, but have revealed little about their programmes, in sharp contrast to the USA's transparency over its PGS effort.

While the USA has stated PGS will only carry a conventional payload, Hilborne says China and Russia may distrust Washington's assurances and there is no agreement in place to prevent the two from arming their hypersonic missiles with nuclear warheads.

China carried out its seventh hypersonic test in April, a similar number to that carried out by the USA, “and as far as we know they were broadly successful”, Hilborne says.

He says that “nuclear weapons are at the core of the Russian perception of power”, so Moscow is more likely to incorporate a warhead of this type to gain an advantage over adversaries with stronger conventional inventories.

“They are very aware of their conventional inferiority, even though they are making advancements in that area,” he says.

Hypersonic technology will not only lend itself to weapons, Hilborne notes, but could also be applied to surveillance aircraft. However, this could “still have the reverse effect [of] what is intended”.

In addition to the payload ambiguity, Hilborne sees a number of characteristics of the technology that could cause alarm in Beijing or Moscow.

The high manoeuvrability of hypersonic weapons compared with ballistic missiles could mean that the target is able to be altered, leading to uncertainty over their intended use.

The boost-glide trajectory of the PGS could also be mistaken for a space weapon, even though it only leaves the earth’s atmosphere for a small amount of time, as is also the case with ICBMs.

“There seems to be a lot of strategic challenges that they entail,” Hilborne adds, noting that their development coincides with heightened tensions between the big three global powers.