The head of NATO has warned that divisions between the U.S. under Donald Trump and its European allies could destroy the trans-Atlantic relationship. Jens Stoltenberg on Tuesday urged the U.S. and Europe to come closer together in the wake of a string of disagreements, including Trump’s baiting of Germany Angela Merkel over immigration, the U.S. departure from the Iran nuclear accord, and Trump’s climate-change policy. “There are real differences between the United States and other allies over issues such as trade, climate change, and the Iran nuclear agreement,” Stoltenberg wrote. “These disagreements are real and they won’t disappear overnight. In fact, nowhere is it written in stone that the trans-Atlantic bond will always thrive. That doesn’t, however, mean that its breakdown is inevitable. We can maintain it, and all the mutual benefits we derive from it.” Trump tweeted Monday that Germans are “turning against their leadership” over immigration and made false claims that its refuge influx was making its crime rate soar.