Wasington, April 28: US Secretary of Defence James Mattis has said that Washington will discuss with allies and Pyongyang the need to retain American troops on the Korean Peninsula. The issue is among those Washington will discuss first with its and then with North Korea, Mattis said on Fridaywhile meeting his Polish counterpart Mariusz Blaszczak at the Pentagon. He added that the US “will build, through confidence-building measures, a degree of trust if it’s going to go forward”, referring to the dialogue with North Korea on the denuclearisation issue, reports Xinhua news agency.