Nasa has called India's destruction of a satellite a "terrible thing" that could threaten the International Space Station (ISS).
The space agency's chief, Jim Bridenstine, said that the risk of debris colliding with the ISS had risen by 44% over 10 days due to the test.
However he said: "The international space station is still safe. If we need to manoeuvre it we will."
India is the fourth country to have carried out such a test.
Prime Minister Narendra Modi announced the test - Mission Shakti - with great fanfare on 27 March, saying it had established India as a "space power".
In an address to employees, Mr Bridenstine sharply criticised the testing of such anti-satellite (ASAT) weapons.
He said that Nasa had identified 400 pieces of orbital debris and was tracking 60 pieces larger than 10cm in diameter. Twenty-four of those pieces pose a potential risk to the ISS, he said.
Our IP Address: