BBC新闻100篇 News Item 58

As leaders from nearly 50 countries meet

in Washington for a major summit on Nuclear Security,

Ukraine has pledged to eliminate stockpile

of highly enriched uranium by 2012.

Ukraine will also convert several nuclear research facilities

to use low enriched uranium.

The summit, the biggest international meeting

hosted by the US since 1945,

has been called by president Obama.

Our diplomatic correspondent

Jonathan Marcus reports from Washington.

The timing may have been choreographed

for the decision by the Ukraine authorities

is just the sort of news president Barack Obama wants to hear.

This summit is all about securing stocks of fissile material,

highly enriched uranium and plutonium

could potentially be used by terrorists

to build a nuclear bomb.

US officials said that Ukraine has sufficient highly enriched uranium

for several nuclear weapons.

This will be removed

with some help from the United States.

This is a precedent Obama

would like other countries to follow

and just to underscore the gravity of the potential threat.

John Briton, a senior US counter-terrorism official,

has warned that al-Qaeda

has been seeking material

for a nuclear bomb

for over 15 years

and that interest remains strong.