The West faces its "most unpredictable security environment in a generation" amid differences between the United States and its allies as well as Russian aggression, NATO Secretary General Jens Stoltenberg said on Thursday.
The bond between NATO members was strong, he said in a speech in London. "But today, some are doubting the strength of that bond."
"We see differences between the United States and other allies over issues such as trade, climate and the Iran nuclear deal.
"And there are disagreements within Europe, too, over the future direction of the European Union, over values and populism," Stoltenberg said.
He acknowledged that "it is not written in stone that the transatlantic bond will survive forever ... But I believe we will preserve it."
"Because we face the most unpredictable security environment in a generation," he said, citing international terrorism, the proliferation of weapons of mass destruction, cyber attacks, and a "more assertive Russia."
Stoltenberg also met British Prime Minister Theresa May on Thursday, after travelling to several other European capitals this month ahead of a NATO summit scheduled for July 11-12 in Brussels.
"The United Kingdom has long continued to lead in NATO and will continue to do so," he told reporters after meeting May.
