If every object orbiting the Earth stayed on a simple path, multiple observations of an object would yield precise estimates of its orbit and position. Unexpected glitches - such as accidental releases of fuel - can shift a satellite's orbit.
But so can the drag from Earth's atmosphere, as well as gravitational tugs from the Sun, Moon, and Earth, which is somewhat squashed in shape. The military uses models of these environmental perturbations to help refine its estimates of satellite orbits.
There are 800 to 1,000 active satellites in orbit and about 17,000 pieces of debris and dead satellites, like the Russian one, that can't be controlled. As per scientists it is simply not possible to calculate all collision points of these floating objects, hence the risk of similar events occurring prevails.