NATO chief urges unity, warns of Russia threat in U.S. address

NATO Secretary General Jens Stoltenberg is applauded by U.S. Vice President Mike Pence and House Speaker Nancy Pelosi (D-CA) as he addresses a joint meeting of Congress in the House Chamber on Capitol Hill in Washington, U.S., April 3, 2019. REUTERS/Carlos Barria

WASHINGTON (Reuters) - The head of the North Atlantic Treaty Organization warned the U.S. Congress on Wednesday of the threat posed by "a more assertive Russia," including a massive military buildup, threats to sovereign states, the use of nerve agents and cyberattacks.

"We must overcome our differences now because we will need our alliance even more in the future. We face unprecedented challenges - challenges no one nation can face alone," NATO Secretary General Jens Stoltenberg said.