A former U.S. top nuclear envoy says North Korea has not transferred any nuclear technology since it helped Syria build a nuclear reactor.

Christopher Hill said the U.S. has continued to negotiate with North Korea, based on its conclusion that Pyongyang has halted nuclear proliferation activities since the Syrian nuclear facility was destroyed by an Israeli air strike in 2007.

He made the remarks at a Senate hearing to confirm his appointment as the U.S. ambassador to Iraq.