berlin germany foreign minister siegmar gabriel meet turkish counterpart mevlut cavusoglu turkey saturday chance discuss strain tie nato ally series diplomatic incidents gabriel cavusoglu discuss bilateral relationships well difficult theme expectations side informal meet turkish city antalya german foreign ministry say twitter without give detail meet come day announcement release german national detain turkey political reason leave tally still jail nine tie two ally deteriorate turkish president recep erdogan launch crackdown political opponents fail coup last year germany criticize mass arrest refuse extradite people turkey say involve plot relations turkey contentious issue talk form coalition government chancellor angela merkel conservative bloc hold two party lose support election september german turkish foreign minister meet detainee release