In Washington for talks at the White House and Pentagon, Stoltenberg made reference to Paris's support for a European defense grouping autonomous from NATO, especially the wake of last month's shock creation of AUKUS, an Australia-Britain-US grouping focused on Indo-Pacific security that left France, and NATO as a group, out.

"I understand that France is disappointed," Stoltenberg said in a conference at Georgetown University.

"What I don't believe in is any efforts to try to do something outside the NATO framework, or compete with or duplicate NATO, because NATO remains the cornerstone, the bedrock for European security and also actually of North American security," he said.

The announcement last month of AUKUS, which included Canberra cancelling an order for French diesel submarines for American nuclear-powered subs, left France and some others in Europe feeling like the NATO alliance had been downgraded in Washington's priorities.

"Europeans must stop being naive" about geopolitical realities, French President Emmanuel Macron said at the time, amid increased talk of a European defense arrangement.

Stoltenberg said the defense of Europe goes beyond its borders.

"It's about geography. Turkey in the south, Norway, Iceland in the north and in the west, US, Canada and the United Kingdom," he said.

"They are important for the protection of defense of the whole of Europe."

"Any attempt to try to weaken the transatlantic bond by creating alternative structures, conveying the idea that we can go it alone, will not only weaken NATO, but it will divide Europe," he said.