US detects ‘highly unusual’ North Korean submarine activity – CNNPolitics

An ejection test examines a missile’s “cold-launch system,” which uses high pressure steam to propel a missile out of the launch canister into the air before its engines ignite. That helps prevent flames and heat from the engine from damaging either the submarine, submersible barge or any nearby equipment used to launch the missile.

http://www.cnn.com/2017/07/31/politics/north-korea-ejection-test-submarine-activity/index.html