U.S. President Barack Obama deeply impressed the Japanese public with the speech he delivered in the world's first atom-bombed city of Hiroshima on May 27. But on his home turf, he is clandestinely pushing a plan to modernize the U.S. nuclear arsenal.

The plan, with its development cost estimated at $1 trillion over the next 30 years, is aimed at downsizing missiles capable of carrying nuclear warheads and improving their mobility with new delivery systems and platforms.

When does Obama expect to achieve a world without nuclear weapons, which he called for again in Hiroshima?