Debris from a Chinese rocket is expected to fall back to Earth in an uncontrolled re-entry this weekend and it is not clear where and when exactly the rocket parts will crash on the surface, according to a BBC report.
Western experts have criticised China for not taking adequate precautions to ensure that the debris does not land in inhabited areas where it can cause harm.
The Long March 5B rocket was launched in late April to carry the first module of China's future space station into orbit. The rocket is currently circling Earth and is poised to enter the lower atmosphere.
The US on Thursday said it was watching the path of the object closely but currently had no plans to shoot it down.
"We're hopeful that it will land in a place where it won't harm anyone," BBC cited US Defence Secretary Lloyd Austin as saying. "Hopefully in the ocean, or someplace like that."
He also indirectly criticised China, saying there was a need to "make sure that we take those kinds of things into consideration as we plan and conduct operations".
Chinese state media has played down fears the rocket might crash on inhabited land, suggesting it will fall somewhere in international waters.
The Global Times quoted aerospace expert Song Zhongping who added that China's space monitoring network would keep a close watch and take necessary measures should damage occur.
The rocket is expected to largely burn up as the atmosphere gets more and more dense at about 60km altitude from the surface. The parts that don't burn up completely will remain and fall to Earth.
If all this happens uncontrolled, the place where the rocket burns up and where the debris will fall can be neither controlled nor accurately predicted, the BBC report said.
A previous launch of a Chinese Long March 5B in 2020 had ended with remains of the rocket re-entering in an uncontrolled way, with some debris crashing in a rural area of Ivory Coast.