"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."

The crew aboard the orbital outpost -- currently four Americans, a German and two Russians -- had to take shelter in their return ships, which is standard procedure in the event of an emergency that might force evacuation.

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.

But in his strongly-worded prepared remarks, Price said the danger was far from over.

"This test will significantly increase the risk to astronauts and cosmonauts on the International Space Station, as well as to other human spaceflight activities," he said.

"Russia's dangerous and irresponsible behavior jeopardizes the long term sustainability of outer space and clearly demonstrates that Russia's claims of opposing the weaponization of space are disingenuous and hypocritical.

"United States will work with our allies and partners to respond to Russia's irresponsible act," he added, while declining to comment on specific measures.

Washington and Moscow have maintained strong space ties since the end of the Cold War, despite increasing political tensions in recent years.

Pentagon spokesman John Kirby also briefed reporters, in a sign of the incident's strategic significance, and stressed that Russia did not give Washington advance warning of the missile.

"We watch closely the kinds of capabilities that Russia has seemed to want to develop, which could pose a threat not just to our national security interests, but the security incentives of other spacefaring nations," he said.

"We've been very clear, we would like to see norms for space so that it can be used responsibly by all spacefaring nations."