The Pentagon has blasted as "disturbing" a Chinese missile launch from its man-made islands in the disputed South China Sea, saying that the test was meant to intimidate other claimants to the strategic waterway.

The move startled analysts, who characterized it as a rarity — if not a first — in the South China Sea, home to crucial international shipping lanes.

"Of course the Pentagon was aware of the Chinese missile launch from the man-made structures in the South China Sea near the Spratly Islands," Pentagon spokesman Dave Eastburn told The Japan Times, calling it "truly disturbing."