The Foreign Ministry says the summoning of Ambassador Ri Si Hong today was also prompted by North Korea's recent firing of several hundred short-range missiles and at least two medium-range missiles, as well as an exchange of fire at sea with South Korea.
The ministry said in a statement that Germany calls on North Korea to take steps to de-escalate the situation and restart international talks on its nuclear programme.
The statement said that if North Korea conducts another nuclear test "a clear reaction" by the international community would follow.