Complex sentence: Mattis stressed that the Alliance should remain "credible, capable and relevant" so that Europeans and Americans could jointly resist the enemies of democracy, and both sides of the Atlantic share the legacy of friendship, freedom, and a trusting alliance.
Split into simpler sentences: Mattis stressed that the Alliance should remain "credible, capable and relevant" so that Europeans and Americans could jointly resist the enemies of democracy. Both sides of the Atlantic share the legacy of friendship, freedom, and a trusting alliance.