Satellites crashing in space - Russian and US satellites

One always thinks of space as a large open area, with plenty of space in all directions. You combine this space with the concept of satellites being well regulated and following controlled orbits, and then it is difficult to believe that satellites under the control of such countries such as the United States and Russia could actually collide, and yet that is exactly what seems to have happened:

The collision between a U.S. and a Russian satellite over Siberia may have been accidental and the first of its kind, but experts say more crashes will inevitably occur and could have geopolitical consequences. "This is an event that really makes us realize that things are not so straightforward as we originally thought," said Francisco Diego, a senior research fellow in physics and astronomy at University College London.
The collision, between a spacecraft operated by U.S. communications group Iridium Satellite LLC and a Russian Cosmos-2251 military satellite, happened 485 miles above the Russian Arctic on Tuesday afternoon. The crash sent at least 600 pieces of debris off into space, officials said, increasing the risk that other satellites, including the vast International Space Station, which orbits 220 miles up, could be struck and damaged.

This crash may have been accidental, but what is to prevent countries from investing in such technologies. For example, a couple of such crashes have the effect of impacting the GPS and communication technologies that are used by the US military to great affect.