North Korea has raised at least one missile into its upright firing position, feeding concerns that a launch is imminent, a U.S. official told CNN Thursday.

This comes amid another round of daily tough talk from the North. A government agency is quoted by the state-run media as saying that "war can break out any moment."

So far, South Koreans -- who've heard the cross-border bombast before -- are taking the swagger in stride. Washington regards much of the North's saber rattling as bluster.