A telecommunications satellite owned by Iridium Satellite and a defunct Russian military communications satellite were destroyed about 485 miles above the Russian Arctic on Tuesday. As a consequence, Russian and U.S. experts say the first-ever collision between two satellites has created clouds of debris that could threaten other unmanned spacecraft.

The collision was between a now-defunct Russian communications satellite launched in 1993 and one of 66 satellites privately owned by Iridium, a Maryland company that provides phone service to customers such as workers on offshore oil platforms.

The international space station does not appear to be threatened by the debris, they said, but it's not yet clear whether it poses a risk to any other military or civilian satellites. However the debris will continue to spread, however, and potentially could force the station to make an avoidance maneuver at some point, said NASA spokesman John Yembrick.

"This is an event that really makes us realize that things are not so straightforward as we originally thought," Francisco Diego, a senior research fellow in physics and astronomy at University College London, told Reuters. "I couldn't put a number on the probability of this happening again, but now that it has happened, it changes things a lot and it becomes a concern."

The collision happened not far from the orbit of a defunct weather satellite blown up by a ground-based missile in a Chinese weapons test in 2007. European and U.S. officials argue the resulting debris made it harder to identify crash risks.

Scientists say predicting collisions is difficult because of the unpredictable behavior of other objects, solar radiation and the gravitational effect of the moon and Earth, while molecular wisps of atmosphere can gently skew orbits.