CNN) -- 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 as the world continued to keep watch for a possible missile launch by the secretive government, and a day before U.S. Secretary of State John Kerry is expected to arrive in the region.
In the latest 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."
The 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.
The official declined to specify what type of intelligence led the United States to conclude the medium-range missile -- a Musudan -- was in a firing position.
The Musudan is an untested weapon that South Korea says has a range as far as 3,500 kilometers (2,175 miles).
It could reach as far as Guam, a Western Pacific territory that is home to U.S. naval and air bases, and where the United States recently said it was placing missile defense systems.
The United States and South Korean militaries have been monitoring the movements of mobile ballistic missiles on the east coast of North Korea.
Japan has deployed defense systems, as it has done before North Korean launches in the past, in case any test-fired missile flies near its territory.