The Soviet Union declared war on Japan on 8th August 1945. On the same day, the United States dropped the second atomic bomb on Nagasaki.
Examples (Wiktionary)
Mandarin
投下原子弹
投下原子彈
tóu xià yuán zǐ dàn
to drop an atomic bomb
Mandarin
军队在沙漠上空投放了三枚原子弹。
軍隊在沙漠上空投放了三枚原子彈。
jūn duì zài shā mò shàng kōng tóu fàng le sān méi yuán zǐ dàn .
The army released three atomic bombs above the desert.
Mandarin
我们现在还没有原子弹。但是,过去我们也没有飞机和大炮,我们是用小米加步枪打败了日本帝国主义和蒋介石的。
我們現在還沒有原子彈。但是,過去我們也沒有飛機和大炮,我們是用小米加步槍打敗了日本帝國主義和蔣介石的。
wǒ men xiàn zài hái méi yǒu yuán zǐ dàn . dàn shì , guò qù wǒ men yě méi yǒu fēi jī hé dà pào , wǒ men shì yòng xiǎo mǐ jiā bù qiāng dǎ bài le rì běn dì guó zhǔ yì hé jiǎng jiè shí de .
We do not have the atom bomb yet. But neither did we have planes and artillery in the past. We defeated the Japanese imperialists and Chiang Kai-shek with millet plus rifles.