A Chinese booster rocket made an uncontrolled return to Earth on Saturday, US Defense Department officials said, as they chided Beijing for not sharing information on the potentially hazardous object’s descent.

US Space Command “can confirm the People’s Republic of China (PRC) Long March 5B (CZ-5B) re-entered over the Indian Ocean at approx 10:45 am MDT on 7/30,” the US military unit said on Twitter, referring to China’s official name.

“We refer you to the #PRC for further details on the reentry’s technical aspects such as potential debris dispersal+ impact location,” it said.

The Long March 5B rocket was used last Sunday to launch an uncrewed spacecraft, named Wentian, carrying the second of three modules China needed to complete its new Tiangong space station.

NASA administrator Bill Nelson criticized Beijing on Twitter Saturday, saying that the failure to share the details of the rocket’s descent was irresponsible and risky.

“All spacefaring nations should follow established best practices and do their part to share this type of information in advance,” Nelson wrote, “to allow reliable predictions of potential debris impact risk, especially for heavy-lift vehicles, like the Long March 5B, which carry a significant risk of loss of life and property.”

He added: “Doing so is critical to the responsible use of space and to ensure the safety of people here on Earth”.

The Tiangong space station is one of the crown jewels of Beijing’s ambitious space program, which has landed robotic rovers on Mars and the Moon and made China only the third nation to put humans in orbit.

The new module, propelled by the Long March 5B, successfully docked with Tiangong’s core module on Monday and the three astronauts who had been living in the main compartment since June successfully entered the new lab.

China has poured billions of dollars into space flight and exploration as it seeks to build a program that reflects its stature as a rising global power.