4 sentences

1. 该国正式向邻国宣战。

   gāi guó zhèng​shì xiàng lín​guó xuān​zhàn.

   The country officially declared war on its neighbor.

   Source: Dong Chinese Dictionary

2. 朝鲜马上就会宣战。

   Cháo​xiǎn mǎ​shàng jiù huì xuān​zhàn.

   North Korea will soon declare war.

   Source: OpenSubtitles

3. 这表示宣战了。

   zhè biǎo​shì xuān​zhàn le.

   This means war.

   Source: OpenSubtitles

4. 这是宣战吗？

   zhè shì xuān​zhàn ma?

   Is this a declaration of war?

   Source: OpenSubtitles