This is the beginning of the end of John's vision. Jesus is speaking. This can be shown clearly as it is in the UDB. (See: [[rc://en/ta/man/jit/figs-explicit]])
It is understood that he is coming in order to judge. See how you translated this in [Revelation 3:11](../03/11.md). Alternate translation: "I am coming to judge soon!" (See: [[rc://en/ta/man/jit/figs-explicit]])