German Chancellor Angela Merkel attends a session of the lower house of parliament Bundestag in Berlin, Germany, April 26, 2018. REUTERS/Axel Schmidt

BERLIN (Reuters) - German Chancellor Angela Merkel said on Friday that NATO’s mutual defense doctrine applied to all member states and added that she was pleased Montenegro was part of that.

U.S. President Donald Trump had suggested that the small Balkan country was not worth defending against attack.