The United States will probably use the Manbij terror attack that took place in the north of Syria recently as a pretext not to withdraw their troops, despite president Donald Trump’s announcement. ISIS serves certain American interests.
Germany’s sovereignty is limited, therefore one cannot expect full participation of its foreign affairs’ minister in international talks. Foreign and military policy of Germany is conducted under US supervision. By urging Russia to destroy a missile system foreign affairs minister of Germany is playing a game: showing America that he is following the US political and informational line. In fact he does not care what will happen with the missiles, it is a long-term question. He understands that it is not necessary to go with the US in all directions – Nord Stream II is more important to Germany.
Recurring pro-Kremlin disinformation narrative about German-American relations. For other examples see: Germany is the executor of US hegemony over Europe; The USA is controlling Europe through occupied Germany; Germany will have to choose between defending Europe's interest and catering to Washington. The disinformation message was a reaction to German Foreign Minister urging Russia to save the IMF treaty by destroying a missile system.