Defense Secretary Ash Carter is pointing to Russia and China as potential threats to global order.

In a speech Saturday at the Ronald Reagan Presidential Library, Carter says the U.S. defense establishment needs to adapt to new challenges, including those posed by China's growing military power and Russia's more aggressive approach in Europe, the Middle East and beyond.

Carter says Russia appears intent on "flouting" principles such as respect for state sovereignty, with its incursions in eastern Ukraine and Georgia.

And he is expressing concern about China's intentions, although he says the U.S. welcomes its modernization. He says the test will be in how China behaves, including its actions in the contested South China Sea, where the U.S. has complained that China is militarizing artificial islands.