Brig. Gen. Neil Tolley, head of all American special-operations forces in South Korea, said units of elite U.S. troops were conducting "special reconnaissance" missions in the North.
Elite troops have been dropped behind North Korean lines to pinpoint the specific locations of Pyongyang's vast network of underground military bases, Tolley said during a speech at a Special Operations Forces Industry Conference in Tampa, Fla., last Tuesday.
Tolley's comments on the American deployments in North Korea were first reported on Monday by The Diplomat, a Japan-based foreign-affairs magazine.
American commandos have identified hundreds of underground munitions facilities, along with thousands of subterranean artillery positions, linked by a complex network of underground tunnels that run up to the Demilitarized Zone that separates North and South Korea, Tolley said.
Until now, U.S. and Western intelligence had not been able to verify the existence of the tunnel network, since the complex had been hidden from spy satellites that continually survey the country.
"There were four tunnels under the [Demilitarized Zone]. Those are the ones we know about," Tolley said, according to reports in the Tampa Tribune.
The one-star general's comments came days after news broke that American special forces were also on the ground in Yemen.
Those troops are providing intelligence and logistics support to the Yemeni military's ongoing offensive to drive al Qaeda's local cell, known as al Qaeda in the Arabian Peninsula (AQAP), from its positions in the southern part of the country.
Defense Secretary Leon Panetta told reporters on May 10 that no American troops would be sent to Yemen as part of that country's counterterrorism operations.
Last Tuesday, DOD spokesman George Little said the U.S. special-forces units in Yemen were part of an American-led advise-and-assist mission supporting the Yemeni military.
When asked if the U.S. role in Yemen could expand beyond intelligence and logistical support, Little replied that the United States has a "very strong military relationship with Yemen [and] that relationship is focused ... on jointly addressing the counterterrorism threat" posed by AQAP.