All nations who possess the Book of Mormon “shall be judged of them according to the words which are written” (2 Nephi 25:21–22). That will eventually be all nations, for the everlasting gospel as contained in the Book of Mormon, shall go to all nations.
6 And I saw another angel fly in the midst of heaven, having the everlasting gospel to preach unto them that dwell on the earth, and to every nation, and kindred, and tongue, and people,
7 Saying with a loud voice, Fear God, and give glory to him; for the hour of his judgment is come: and worship him that made heaven, and earth, and the sea, and the fountains of waters. [Revelation 14:6–7]
The hour of the Lord’s judgment began with the coming forth of the Book of Mormon. Joseph Smith did begin to smite the earth with the Book of Mormon—the rod of his mouth. Of course, the judgment spoken of is positive as well as negative.
13 Therefore, having so great witnesses, by them shall the world be judged, even as many as shall hereafter come to a knowledge of this work.
14 And those who receive it in faith, and work righteousness, shall receive a crown of eternal life;
15 But those who harden their hearts in unbelief, and reject it, it shall turn to their own condemnation—
16 For the Lord God has spoken it; and we, the elders of the church, have heard and bear witness to the words of the glorious Majesty on high, to whom be glory forever and ever. Amen. [D&C 20:13–16]
In Isaiah’s words, “the rod of his mouth” is the word of God. Nephi saw “that the rod of iron … was the word of God” (1 Nephi 11:25; see also JST, Revelation 2:26–27; 12:5; 19:15). Through the word of God will come “equity for the meek of the earth” (a crown of eternal life), and “slay the wicked” (condemnation and not receive eternal life).