Which of America’s adversaries will test Trump first?

This leaves the most worrisome adversary of all: China. While Washington and Beijing have had tense security relations for a number of years, particularly as China moved to assert control over parts of the South China Sea, the two nations were economically intertwined and shared an interest in regional and global stability. Now relations between the two may be disintegrating quickly. Throughout the presidential campaign, Trump was highly critical of what he sees as the inequity in the U.S.-China economic relationship. Since winning the election, he has questioned the longstanding “one China” policy that recognizes Beijing, and not Taiwan, as the sole diplomatic representative of the Chinese nation.

More recently, Rex Tillerson, Trump’s nominee for secretary of state, said in his Senate confirmation hearings that China’s access to islands it has been building in the oil- and gas-rich South China Sea is “not going to be allowed.” He compared China’s policy of building islands and then using them as the basis for legal claims to large parts of the South China Sea to Russia’s annexation of Crimea in 2014.

Since both Trump and his secretary of state-nominee are taking the hardest line toward Beijing since President Richard Nixon’s opening to China in the 1970s, the potential for crisis or conflict is high. China considers Taiwan and the South China Sea vital national interests and hence would go to great lengths to defend its position, possibly even using military force. And unlike America’s other adversaries, China has multiple ways of hurting the United States, including not only military action but also economic pressure and cyber aggression.