He said Pyongyang had been "conciliatory and forthcoming" in the past, only to backtrack. "I believe that it is important not to reward North Korea solely for agreeing to have a dialogue," Onodera stressed at a major security summit in Singapore.
Meanwhile, The Canadian defense minister said there were no plans in Seoul or Washington to topple North Korea's government or speed up its reunification with the South.
"There is no plan to seek a regime change or collapse in North Korea. There is no plan to seek accelerated reunification, they don’t seek an excuse to send troops north of the 38th parallel," Harjit Singh Sajjan said at the summit.
He said allowing Pyongyang to hold on to nuclear weapons could "embolden" other non-nuclear nations to attempt to develop their own atomic programs.
South Korea’s National Defense Minister Song Youngmoo said earlier Seoul had a policy of three no’s on North Korea: no desire for North Korea's collapse, no pursuit of unification by absorption, and no pursuit of unification through artificial means.