WASHINGTON — With a second U.S.- North Korea nuclear summit looming in February, researchers have discovered a secret ballistic missile base in North Korea — one of as many as 20 undisclosed missile sites in the country, according to the researchers’ new report.

The Kim regime has never disclosed the existence of the Sino-ri Missile Operating Base to the outside world. Ballistic missiles are the primary delivery mechanism for North Korean nuclear warheads.

The report from Beyond Parallel, a project sponsored by the Center for Strategic and International Studies (CSIS), a defense think tank, was released Monday and comes after an announcement Friday that President Donald Trump "looks forward" to meeting with Chairman Kim Jong-Un next month "at a place to be announced at a later date." NBC News is reaching out for White House reaction.