The chiefs of the Korean and U.S. Marine Corps have discussed ways to expand military cooperation and joint drills in a bid to strengthen their combined defense readiness posture, officials said Thursday. Lt. Gen. Ju Il-suk held talks with his U.S. counterpart, Gen. Eric M. Smith, at the Pentagon, near Washington, on Tuesday (local time), according to Korea's Marine Corps. The two sides shared the understanding that the allies' Marines will make…