BERLIN (Reuters) - The German government condemned Tuesday s firing of a ballistic missile by the Houthi militia toward Riyadh, calling for an immediate ceasefire and U.N.-led peace negotiations.  We condemn the renewed missile launch from Yemen against the capital of the kingdom of Saudi Arabia in the strongest terms,  a foreign ministry spokesman said.  There can be no justification for such an act. The missile attacks on Saudi Arabia must finally stop.  The spokesman said the Yemen conflict could only be solved through diplomatic means.  We urge the parties to adopt an immediate ceasefire and to negotiation under the aegis of the United Nations.  