berlin relations berlin washington difficult phase unite state big good current spat show tie improve german foreign minister sigmar gabriel say tuesday true difficult situation relations unite state germany gabriel say unite state old big current conflict think return good relations future things get trivialize think inappropriate communicate beer tent twitter gabriel add berlin chancellor angela merkel tell bavarian ally beer tent munich sunday europe could long completely rely ally u.s. president donald trump respond criticize germany via twitter early tuesday germany 's gabriel say tie u.s. 'difficult improve