国际英语新闻：U.S. unveils nuclear forces structure

The White House also said the United States will invest well over 100 billion dollars in nuclear delivery systems to sustain existing capabilities and modernize some strategic systems over the next decade.

Under the START, the United States and Russia are to slash their strategic nuclear warheads to 1,550 each over seven years, about a third less than currently permitted, and the number of delivery vehicles -- missiles, bombers -- will be brought down to 700-800.

The Pentagon earlier this month unveiled the size of U.S. nuclear arsenal for the first time, saying it has a total of 5,113 nuclear warheads in its stockpile.

The White House said the new structure is based on the policies and principles in the Nuclear Posture Review and describes a " comprehensive plan for sustaining a strong nuclear deterrent for the duration of the New START Treaty and beyond."