Good luck transporting them across the world.
According to information I pulled from Wikipedia (because I am lazy and cannot be assed to look for other sources) the KPA has, of 2010 (so heavily outdated information) 1,106,000 active personnel and 8,200,000 reserve personnel. The KPA does not use aircraft carriers but possesses Il-76MD strategic airlifters with a strategic carry capacity of 6,000 troops, and a naval carry capacity of 15,000. Also according to Wikipedia, "The Korean People's Army operates a very large amount of equipment, including 4,100 tanks, 2,100 APCs, 8,500 field artillery pieces, 5,100 multiple rocket launchers,[38] 11,000 air defense guns and some 10,000 MANPADS and anti-tank guided missiles[50] in the Ground force; about 500 vessels in the Navy[38] and 730 combat aircraft in the Air Force,[38] of which 478 are fighters and 180 are bombers.[51] North Korea also has the largest special forces in the world, as well as the largest submarine fleet.[52] The equipment is a mixture of World War II vintage vehicles and small arms, widely proliferated Cold War technology, and more modern Soviet or locally produced weapons."
So really, the KPA is a moderate threat. Most of their equipment is outdated though, so I couldn't really quite see them getting too far.
Plus they have extremely outdated equipment.
Their total vehicular numbers seem around the level of the total number of vehicles and artillery pieces deployed during Operation Barbarossa where applicable which. Which isn't that impressive.