SIMI VALLEY, Calif. (AP) — Defense Secretary Ash Carter is accusing Russia of endangering world order, citing its incursions in Ukraine and loose talk about nuclear weapons, and he says the U.S. defense establishment is searching for creative ways to deter Russian aggression and protect U.S. allies.

In remarks at the Ronald Reagan Presidential Library after eight days of travel in Asia, Carter also expressed concern about China's expanding influence and growing military might. But he reserved his stronger words for Russia.

Carter said Russia is undertaking "challenging activities" at sea, in the air, in space and in cyberspace.

His remarks were perhaps the strongest he has expressed about America's former Cold War foe.

After more than two decades of dominating great-power relations, the United States is seeing Russia reassert itself and China expand its military influence beyond its own shores. Together these trends are testing American pre-eminence and its stewardship of the world order.

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