SDI stands for Strategic Defense Initiative. It was a US military plan that President Reagan started in 1983. The idea was to build special weapons — many of them on satellites in space, some using lasers — that could destroy another country’s missiles before those missiles reached America.

SDISDI stands for代表的是 Strategic Defense Initiative「Strategic Defense Initiative」（戰略防禦計畫）。 It was a US military plan它是一個美國的軍事計畫， that President Reagan started in 1983由雷根總統在1983年提出。 The idea was to build special weapons這個構想是要打造特殊的武器 — many of them on satellites in space, some using lasers —──很多裝在太空的衛星上，有些會用到雷射── that could destroy another country’s missiles before those missiles reached America能在別國的飛彈抵達美國之前就把它們摧毀。

Newspapers nicknamed it Star Wars, after the films, because the picture in people’s heads was space lasers shooting down rockets.

Newspapers nicknamed it Star Wars報紙把它取了個綽號叫Star Wars（星際大戰）， after the films就是借用那系列電影的名字， because the picture in people’s heads was space lasers shooting down rockets因為大家腦中浮現的畫面就是太空雷射把火箭打下來。

Many scientists said it would not work, or would cost far too much, and it was never built as a finished shield in the sky. It still mattered in the 1980s, because the Soviet Union had to take it seriously in talks.

Many scientists said it would not work, or would cost far too much很多科學家說這行不通，或者要花太多錢， and it was never built as a finished shield in the sky它也從來沒有真的變成一個完成的天空防護罩。 It still mattered in the 1980s它在1980年代仍然很重要， because the Soviet Union had to take it seriously in talks因為蘇聯在談判時不得不認真看待它。

If you meet SDI in a history book, it is that Reagan-era plan, not a general word for “defence” and not a later missile programme with a different name.

If you meet SDI in a history book如果你在歷史課本裡遇到SDI， it is that Reagan-era plan指的就是那個雷根時代的計畫， not a general word for “defence”不是泛指「defence（防禦）」的普通用詞， and not a later missile programme with a different name也不是後來另一個名字的飛彈計畫。