North Korea leader Kim Jong Un smiles as he visits Sohae Space Center in Cholsan County, North Pyongan province for the testing of a new engine for an intercontinental ballistic missile (ICBM) in this undated photo released by North Korea's Korean Central News Agency (KCNA) on April 9, 2016. REUTERS/KCNA

WASHINGTON (Reuters) - North Korea is struggling with getting its intercontinental ballistic missile program “up and operational” but it could acquire the capabilities over time, a U.S. military official told a U.S. Senate panel on Tuesday.

“They are struggling with getting the program up and operational, but it is very clear ... over time, I believe, we are going to see them acquire these capabilities if they are not stopped,” Army General Vincent Brooks said.

Brooks has been nominated to be the next commander of U.S. forces in South Korea.