SEOUL, July 18 - The United States is ready to hold talks with North Korea if the conditions are right but will also press UN sanctions to punish Pyongyang for its nuclear and missile tests, a senior US envoy for Asia said on Saturday.

North Korea, which tested a nuclear device in May, has said it was boycotting often stalled six-country talks on ending its nuclear arms programme and will expand its nuclear arsenal in order to defend itself against a ”hostile” United States.