Speaking at a news conference in Honolulu with Japan's foreign minister, Clinton said recent Chinese restrictions on sales of rare earths served as a "wake-up call" for the international community, which has increasingly relied on China for the production of the minerals.
Clinton and Japanese Foreign Minister Seiji Maehara both called for developed countries to diversify the sources of rare earths, 97 percent of which are controlled by China.
Clinton is in Hawaii, where she is meeting top brass from the U.S. Pacific Command and Japan's foreign minister to discuss regional security issues dominated by an increasingly assertive China.
Clinton arrived in Honolulu on Wednesday at the start of a seven-nation trip to Asia that is aimed at cementing ties with some of China's nervous neighbors. It's part of the Obama administration's efforts to counter Beijing's growing clout in a region where America has traditionally been the dominant power.
Before leaving for Vietnam on Thursday, Clinton will meet with U.S. Pacific Command chief Adm. Robert Willard, and deliver a speech on America's leadership role in the Asia-Pacific region.