Three-quarters of the artillery deployed near Pyongyang is close to inoperable, South Korean Broadcaster Munhwa Broadcasting Corporation (MBC) reported on Monday, based on classified documents from 2010 to 2013 allegedly obtained from a source in the North Korean army.

“More than 75% of artillery and war-fighting instruments deployed after a combat readiness inspection by the Korean People’s Army (KPA) General Staff, was harshly criticized for getting rusty and being stained,” MBC showed the document as having read.

South Korea’s Joint Chiefs of Staff (JCS) wasn’t available to immediately comment on the claims.

“We need to further examine the documents,”