The US has condemned Russia for conducting a "dangerous and irresponsible" missile test that it says endangered the crew aboard the International Space Station (ISS).
The test blew up one of Russia's own satellites, creating debris that forced the ISS crew to shelter in capsules.
The station currently has seven crew members on board - four Americans, a German and two Russians.
The space station orbits at an altitude of about 420km (260 miles).
"Earlier today, the Russian Federation recklessly conducted a destructive satellite test of a direct ascent anti-satellite missile against one of its own satellites," US state department spokesman Ned Price said at a briefing.
"The test has so far generated over 1,500 pieces of trackable orbital debris and hundreds of thousands of pieces of smaller orbital debris that now threaten the interests of all nations."
NASA Administrator Bill Nelson said he was outraged at the incident.
"With its long and storied history in human spaceflight, it is unthinkable that Russia would endanger not only the American and international partner astronauts on the ISS, but also their own cosmonauts" as well as Chinese "taikonauts" aboard China's space station, he said in a statement.
Russian space agency Roscosmos downplayed the incident.
"The orbit of the object, which forced the crew today to move into spacecraft according to standard procedures, has moved away from the ISS orbit. The station is in the green zone," the agency tweeted.
The wayward material passed by without incident, but its origin is now under the spotlight.
It appears to have come from a broken-up Russian satellite, Kosmos-1408. A spy satellite launched in 1982, it weighed over a tonne and had ceased working many years ago.
LeoLabs, a space debris-tracking company, said its radar facility in New Zealand had picked up multiple objects where the long-defunct spacecraft should have been.
Mr Price described the Russian action as "dangerous and irresponsible" and said it demonstrated the country's "claims of opposing weaponisation of space are disingenuous and hypocritical.
"The US will work with our partners and allies to respond to their irresponsible act," he said.
And Ben Wallace, UK Defence Secretary, said the test "shows a complete disregard for the security, safety and sustainability of space".
"The debris resulting from this test will remain in orbit putting satellites and human spaceflight at risk for years to come," he added.