NATO is concerned about support Russia could provide for North Korea's missile and nuclear programs, the alliance's head said on Tuesday as Russian President Vladimir Putin headed to the reclusive nuclear-armed country for the first time in 24 years.

The institute estimated that North Korea is focusing on developing an arsenal of tactical nuclear weapons, which could be used early in a conflict, allowing the aggressor to destroy targets without causing significant radioactive fallout.

The Russian president’s visit serves a dual purpose for the two leaders—each wants to extract more from the other while rattling the West, say analysts.