United States President-elect Donald Trump’s choice for secretary of state has suggested a U.S. policy that could create serious disagreement with China. Rex Tillerson said China should be barred from the islands it has built in the South China Sea. Tillerson is former chairman of the oil company ExxonMobil. He spoke to the U.S. Senate Foreign Relations Committee on Wednesday during his confirmation hearing. “China’s island building in the South China Sea is an illegal taking of disputed areas without regard for international norms.” Tillerson told the committee that China’s island building -- and its efforts to place military equipment on those islands -- was similar “to Russia’s taking Crimea” from Ukraine. He added: “We’re going to have to send China a clear signal that, first, the island-building stops; and, second, your access to those islands also is not going to be” permitted. China claims most of the waters of the South China Sea. Brunei, Malaysia, the Philippines and Vietnam also have claims. So does the government in Taiwan. The South China Sea is considered to be rich in natural resources, including oil. It is also an important shipping passage, with an estimated $5 trillion in trade passing through its waters.