He also urged the international community to "stand as one." Steinmeier believes that with tensions between the North and the US rising, it is essential to involve China and Russia to further the aim of nuclear disarmament. Steinmeier said the issue threatened the whole world, not just the Koreas.
At a Wednesday meeting with Japanese leaders in Tokyo, Steinmeier remained skeptical as to Pyongyang's current conciliatory tone, warning against "unrealistic expectations" regarding North Korean leader Kim Jong Un.
In Seoul, Steinmeier emphasized Germany's past as a divided country, saying that "we feel a tremendous solidarity and empathy when we speak about peace and détente on the Korean peninsula."
Koreas agree joint hockey team
"We Germans know what it is like to live in a divided country," he said, adding that German history showed that it is "worth remaining hopeful."
Steinmeier presented Moon with a portrait of Willy Brandt, a former German chancellor, whose "Ostpolitik" Cold War policies paved the way for reconciliation with East Germany, the Soviet Union and other former Warsaw Pact nations.
Moon, meanwhile, congratulated Steinmeier on the grand coalition agreement reached in Berlin on Wednesday, in which he said Steinmeier "played a big role." Steinmeier replied that he was aware that many abroad were waiting anxiously for a new governemnt to form in Germany.
"I think that now we've at least taken another step forward," he said in Seoul. The coalition agreement has yet to be approved by the Social Democrats' members.
On to the Olympics
Steinmeier is due to attend the opening ceremony of the Winter Olympics, which start in Pyeongchang on Friday. In a rare show of rapprochement, North Korea's delegation was given a festive welcome at the Games on Thursday. Its anthem, which is usually banned in the South, was also played.
In addition, Seoul and Pyongyang have sent a joint women's ice hockey team to the Games. What's more, athletes from both countries will march together under a single, neutral flag at the opening ceremony on Friday.