NATO Secretary-General Jens Stoltenberg said the 30-country alliance, established in the wake of World War II to counter the geopolitical ambitions of the then-Soviet Union, was at a "pivotal moment" in its 72-year history. And Biden told the bloc's leaders as he arrived for the one-day meeting in Brussels, that he wanted to "make it clear" that "NATO is critically important for U.S. interests."