And we no longer worry about Soviet nuclear bombs raining down on us.

Landau calculated the dynamics of the first Soviet thermonuclear bomb, including predicting the yield.

He was the chief designer of the Soviet atomic bomb, and worked in the Soviet nuclear program for many years.

That's because the walls were built to keep out not just water, but the blast from a 10,000lb Soviet bomb.

Now they tell me those were Soviet bombs.

Large numbers of unexploded Soviet bombs are also reported to litter the countryside.

He said any terrorist attack now would be more manageable than the damage from Soviet bombs.

The situation, after the first Soviet atomic bomb was detonated in 1949, considerably sooner than expected, changed drastically.

In the following year a second salvo of Soviet bombs hit US cities.

They produced the Plutonium fuel that was used for the first Soviet atomic bomb, amongst other things.