There appears to be described in scripture a period of time when the messiah's reign extends not only over Israel but over all the nations, which he will temporarily rule with a rod of iron:

> Psa_2:9  Thou shalt break them with a rod of iron; thou shalt dash
> them in pieces like a potter's vessel. 
> 
> Rev_2:27  And he shall rule them with a rod of iron; as the vessels of
> a potter shall they be broken to shivers: even as I received of my
> Father. 
> 
> Rev_12:5  And she brought forth a man child, who was to rule all
> nations with a rod of iron: and her child was caught up unto God, and
> to his throne.
> 
> Rev_19:15  And out of his mouth goeth a sharp sword, that with it he
> should smite the nations: and he shall rule them with a rod of iron:
> and he treadeth the winepress of the fierceness and wrath of Almighty
> God.

Zechariah seems to be describing the final denouement of history when God himself rules over all the nations of the earth and the messiah, as king of Israel is a subject king. Paul seems to allude to this passage:

> 1Co 15:24  Then cometh the end, when he shall have delivered up the
> kingdom to God, even the Father; when he shall have put down all rule
> and all authority and power.  1Co 15:25  For he must reign, till he
> hath put all enemies under his feet.  1Co 15:26  The last enemy that
> shall be destroyed is death.  1Co 15:27  For he hath put all things
> under his feet. But when he saith all things are put under him, it is
> manifest that he is excepted, which did put all things under him.  1Co
> 15:28  And when all things shall be subdued unto him, then shall the
> Son also himself be subject unto him that put all things under him,
> that God may be all in all.

The phrase "that God may be all in all" seems to me to be a reference to Zechariah 14:9 and how it shall be fulfilled in harmony with the passages that say that messiah reigns forever:

> Rev 11:15  And the seventh angel sounded; and there were great voices
> in heaven, saying, **The kingdoms of this world are become the
> kingdoms of our Lord, and of his Christ; and he [God] shall reign for
> ever and ever.**  Rev 11:16  And the four and twenty elders, which sat
> before God on their seats, fell upon their faces, and worshipped God, 
> Rev 11:17  Saying, We give thee thanks, **O Lord God Almighty, which
> art, and wast, and art to come; because thou hast taken to thee thy
> great power, and hast reigned.**  Rev 11:18  And **the nations were
> angry, and thy wrath is come**, and the time of the dead, that they
> should be judged, and that thou shouldest give reward unto thy
> servants the prophets, and to the saints, and them that fear thy name,
> small and great; and shouldest destroy them which destroy the earth.
> 
> Psa_10:16  **The LORD is King for ever and ever: the heathen are
> perished out of his land.**
> 
> Psa_29:10  The LORD sitteth upon the flood; yea, **the LORD sitteth King
> for ever.**
> 
> Luk 1:31  And, behold, thou shalt conceive in thy womb, and bring
> forth a son, and shalt call his name JESUS.  Luk 1:32  He shall be
> great, and shall be called the Son of the Highest: and the Lord God
> shall give unto him the throne of his father David:  Luk 1:33  **And he
> shall reign over the house of Jacob for ever; and of his kingdom there
> shall be no end.**