A careful consideration of the various texts in the Old Testament that mention the "angel of the LORD" (KJV) or the "angel of Jehovah" (ASV) reveals that this being was not of the ordinary angel class.
The Angel of Jehovah promised to multiply Hagar's seed, and she confessed, "You are a God who sees" (Gen. 16:10, 13). The Messenger told Abraham, "By myself, I have sworn, says Jehovah" (Gen. 22:15-16). He identified himself as "the God of Bethel" (Gen. 31:11, 13). The Messenger was distinct from God, and yet he clearly possessed the traits of a deity.
A very strong case can be made for the view that this person was the pre-incarnate Word (Jn. 1:1), who became flesh in the form of Jesus Christ (Jn. 1:14). John the Baptizer was to prepare the way for the "messenger of the covenant" (Mal. 3:1), which, according to the New Testament, was Christ (Mt. 11:10).
Jehovah promised Israel that his "angel" (messenger) would be with them in the wilderness (Ex. 23:20ff), and Paul speaks of the presence of Jesus on behalf of the nation as they wandered in Sinai (1 Cor. 10:4).