Here is the report.
Three interceptor ships near Japan and the Philippines, as well as U.S.-based interceptors, are ready to shoot down the North Korean missile if space-, land-, and sea-based sensors determine its flight path is targeted at the United States or U.S. allies, said officials who spoke on condition of anonymity.
The BBC also reports that Japan is on alert to hit any missiles from Korea.
Last Friday, Japanese Defence Minister Naoki Tanaka issued an order to intercept the rocket if it threatened Japan's territory.
South Korea also warned earlier last week that it might shoot down any North Korean rocket that strayed into its territory.
But satellite images taken last Wednesday indicated that work at the Tongchang-ri launch site in North Korea was under way, a US university said.
The controversial launch comes only weeks after North Korea agreed to return to talks on its nuclear programme in return for food aid from the US - a deal which is now on hold.