The U.S. Special Operations Command Korea conducted a joint drill with South Korea's Special Warfare Command forces at Gunsan Air Base in November to practice infiltrating North Korea and capturing its leaders in an emergency.

The drill was a regular training event, but Pentagon unprecedentedly released some images from it last week amid growing concerns about a possible North Korean provocation.

Pyongyang has dropped heavy hints at a provocation ahead of a year-end deadline for the resumption of nuclear talks with the U.S.

The images show that they conducted a static line jump from a CH-47 Chinook helicopter and close-quarters battle training.

Earlier the U.S. military posted a video clip showing a mock gunfight between combined South Korea-U.S. forces and imaginary North Korean troops, but it was later deleted.

The U.S. military had not made public any military exercises that could agitate the North since Washington began talks with Pyongyang last year.

South Korean military authorities admitted that special troops of the two countries are conducting small-scale joint drills on a regular basis but refused to give details citing security reasons.