But he said movement toward that objective should be gradual and should require other nuclear-armed countries to cut their arsenals as well.

VOA: standard.2009.12.25

Like when they devised the first engines or the first nuclear reactors, it didn't work so well at first and then from the experience of many people working on it, over many years, a body of knowledge emerges and that's what we call technology.

这和发明出第一个发动机,或者第一个核反应堆时一样,最开始总是存在很多问题,但随着很多人不断努力去完善它,一种理论体系才得以不断发展,这就是我们所说的科技

耶鲁公开课 - 金融市场课程节选

(Recording) He says the prospect of a summit depends on progress on the North Korean nuclear issue, as well as the state of inter-Korean relations.

VOA: standard.2009.10.23

So both sides have gone well below the original START-One ceilings for their nuclear forces."

VOA: standard.2009.12.07

Mr.Obama discussed nuclear non-proliferation in the Oval Office Tuesday with former secretaries of state George Shultz and Henry Kissinger, as well as former Defense Secretary William Perry and Sam Nunn, former chairman of the Senate Armed Services Committee.

VOA: standard.2009.05.19

(Speech) Mr.Medvedev says facilities for oil and gas production, which guarantee the lion's share of Russian budget revenues, nuclear weapons, which ensure national security, as well as the country's industrial and public utility infrastructure were for the most part created by Soviet specialists.

VOA: standard.2009.11.12