The escalating rivalry between the world's two most powerful countries, which has spread across the globe in recent years, has now expanded beyond the earthly, into the realms of the heavenly.
As China has become deeply embroiled in strategic competition with the US - while heading towards outright hostilities with other regional neighbors - Washington's alarm over the pace of its progress in space is growing louder.
Beijing has made no secret of its ambitions, and a wave of recent successful space missions has shown that the government's rhetoric is backed by technological advances.
Related: 'We are in a space race': NASA sounds the alarm about Chinese designs on the moon
On Friday, China launched a robotic spacecraft for a round trip to the far side of the moon, in a technically demanding mission that will pave the way for an inaugural Chinese crewed landing and a base on the moon's south pole. The Chang'e-6 aims to bring back samples from the side of the moon that is permanently turned away from Earth.
Earlier this week saw the launch of Shenzhou-18, Beijing's latest manned spacecraft mission to the Tiangong Space Station, which was developed after China was excluded from the International Space Station.
Along with the three taikonauts, a living fish, sometimes referred to as "the fourth crew member," was part of the crew. The zebrafish is part of an experiment to test the viability of a large closed ecosystem, involving fish and algae, to help humans live in space for long periods of time.
But collecting lunar samples and zebrafish viability are not the only focus for China's space sector.
The pace of China's ambitions has raised concerns among the administration's main rival, the US, about Beijing's geopolitical intentions, amid what the head of NASA has called a new "space race".
Last week, NASA chief Bill Nelson said the US and China were "basically in a race" to return to the moon, and he feared China was seeking to make territorial claims.
"We believe that a large part of their so-called civilian space program is a military program," he told US lawmakers.
There are concerns about China's development of counter-space weapons, including missiles that can target satellites and spacecraft that can deorbit satellites.
"At a geopolitical level, China's space ambitions raise questions about how the country might use its space capabilities to advance its regional and domestic political and military interests," said Dr. Svetla Ben-Itzhak, deputy director of the West Space Scholars Program from Johns Hopkins University.
General Stephen Whiting of the US Space Command told reporters last week that China's progress was "cause for concern", noting that the number of spy satellites in orbit had tripled in the past six years.
'It's the wild, wild west'
The US and China are indeed in a race, says Prof. Kazuto Suzuki of the University of Tokyo's Graduate School of Public Policy, but it is not about simply putting feet on the moon, as during the Cold War. Rather, it is about finding and controlling resources, such as water.
"It is a race for who has the better technical capabilities. China is quickly catching up. The pace of Chinese technological development is the threatening element [to the US]," he says.
Suzuki says international agreements do not allow national appropriation of resources on the moon, but in reality "it's the wild, wild West."
"In general, China wants to be first so that they have the right to dominate and monopolize the resources. If you have the resources, you have a huge advantage in the future of space exploration."
The US and China are leading the development of separate lunar space station programs. The US-led Artemis program includes plans for a 'Lunar Gateway', a station in lunar orbit as a communications and accommodation center for astronauts, and a science laboratory.
However, the Americans are "not that interested in owning the moon because they've been there," Suzuki says.
"They know it's not really a habitable place, they're more interested in Mars. For them, the Lunar Gateway is a kind of gas station for the journey to Mars." If the Artemis program can extract water from the moon, it could be processed to make rocket fuel from hydrogen and oxygen.
China and Russia, on the other hand, announced joint plans in 2021 to build a shared research station on the moon's surface. The International Lunar Research Station (ILRS) would be open to all interested international parties, they said. However, the US is unlikely to be among them, given its poor relations with both China and Russia.
Suzuki says the China-Russia station "should serve as the Antarctic research station," which is within the rules of international space treaties. "But if it turns out to be a station on which their territorial claims are based, then that is against the rules."
The US is rallying allies to ensure that China does not win the space race. Earlier this month, not long after China announced its intention to land a person on the moon, US leader Joe Biden and his Japanese counterpart Fumio Kishida promised to send an astronaut from Japan - China's historical rival - to the moon to be sent during NASA's Artemis missions in 2028 and again in 2032.
But China is also gathering allies. It has partnerships or financial interests in projects in the Middle East and Latin America, and a dozen international members for its ILRS.
But Ben-Itzhak notes that there are some overlapping memberships. Also, "neither bloc has introduced exclusionary practices so far, which is promising."
Ben-Itzhak says the US and China are indeed in a race, but the term does not fully capture the "complex, nuanced dynamics currently unfolding in the space, in terms of the diverse and increasing number of actors and initiatives, and no clear end goal in sight."
"The real challenge in space isn't just about achieving a specific milestone, like planting flags or collecting rocks; it's about building a sustainable, resilient presence in an incredibly challenging environment. This is a test of our own capabilities."
Additional research by Chi Hui Lin
