WASHINGTON >> The United States cautioned China Thursday that it will meet its defense commitments to allies as tensions mount over territorial disputes in the South China Sea.

Assistant Secretary of State Daniel Russel told a congressional hearing that some Asian countries fear that Russia’s annexation of Crimea could serve as a precedent for Beijing.

In China’s most recent assertive display, its coast guard ships attempted to interdict a Philippine vessel resupplying a small offshore garrison in the Second Thomas Shoal.

The Philippines is a U.S. treaty ally and one of several nations with conflicting territorial claims with China over small islands and reefs in the South China Sea, most of which China claims for itself.

“There should be no doubt about resolve of the United States. We stand by our allies and we stand by our commitments,” Russel, the top U.S. diplomat for East Asia, told a Senate panel that oversees policy to the region.

Russel said China’s “intimidating steps” toward the Philippines appeared to reflect its “anger and discontent” over the Philippines filing a claim at an international tribunal over the weekend challenging China’s claims. He urged China to clarify its claims in the South China Sea and reiterated U.S. support for a diplomatic solution.

Brunei, Malaysia, Vietnam and Taiwan also have territorial claims in the South China Sea.

The Obama administration has struck a more robust tone in recent weeks about China’s behavior, accusing it of incremental steps to change the status quo in disputed areas, also in the East China Sea, where U.S. ally Japan and China are at loggerheads over sovereignty of Japanese-held islands.

Later this month, President Barack Obama will visit the Philippines on a four-nation trip to revive his administration’s foreign policy shift toward Asia that was partly conceived to counter China’s rise in a region where the U.S. has long been the predominant military power. Obama will also visit Japan, South Korea and Malaysia.

Russel said Russia’s annexation of Crimea has heightened concern, particularly among some Southeast Asian nations, about the possibility of China “threatening force or other forms of coercion to advance their territorial interests.”

China needs to demonstrate its commitment to peacefully resolving its territorial disputes, he said.

Russel added that China is economically interdependent with the U.S. and Asian neighbors, and the prospect of the kind of sanctions that have been imposed against Russian banks and government cronies should have a “chilling effect on anyone in China who might contemplate the Crimea annexation as a model.”

China says its claims in the South China Sea have a solid historic and legal basis although these islands extend into the 200-nautical mile exclusive economic zones of other nations. It has rejected the Philippine attempt to seek international arbitration, saying they should hold bilateral negotiations instead.