South Korea, U.S. warn of punishment for North Korea; U.S. stresses sanctions

South Korean Army K1A1 and U.S. Army M1A2 tanks fire live rounds during a U.S.-South Korea joint live-fire military exercise, at a training field, near the demilitarized zone, separating the two Koreas in Pocheon, South Korea April 21, 2017. Picture taken on April 21, 2017. REUTERS/Kim Hong-Ji

WASHINGTON (Reuters) - U.S. President Donald Trump said a "major, major conflict" with North Korea was possible over its nuclear and ballistic missile programmes, while China said the situation on the Korean peninsula could escalate or slip out of control.

Trump, speaking to Reuters on Thursday, said he wanted to resolve the crisis peacefully, possibly through the use of new economic sanctions, although a military option was not off the table.