An international tribunal ruling next week on a challenge to China's expansive claims in the South China Sea could determine whether the region is ruled by law or "raw calculations of power," U.S. officials said Thursday.

But the officials testifying at a congressional hearing declined to say whether any move by China to militarize more disputed land features would prompt a U.S. military response.

The Permanent Court of Arbitration will rule next Tuesday in the case brought by the Philippines, a U.S. ally. China is boycotting the case in The Hague-based court and says it will not accept the verdict.

Abraham Denmark, deputy assistant secretary of defense for East Asia, urged both parties to comply with the ruling.

Denmark said it would be chance to determine "whether the Asia-Pacific's future will be defined by adherence to international laws and norms that have enabled it to prosper, or whether the region's future will be determined by raw calculations of power."

Rep. Randy Forbes, the Virginia Republican who chairs the House subcommittee on sea power, said the world is watching whether China behaves like a responsible stakeholder in the international system, and, if not, to see how America responds.

"What we do — or don't do — to support our allies and the rules-based international system in the weeks ahead will have echoes across the region and in other corners of the globe," Forbes said.

China claims most of the South China Sea, including islands far from its mainland, where the Philippines, Brunei, Malaysia, Taiwan and Vietnam also have claims. China asserts it has historic rights of sovereignty and that the tribunal lacks jurisdiction as it did not consent to arbitration. It also says that the U.S. has no business intervening as it is not party to the disputes.

The U.S., however, says it has a stake in ensuring freedom of navigation and commerce in seas that carry more than half the world's merchant fleet tonnage. Senior State Department official Colin Willett told the hearing that the U.S. will not hesitate to defend its national security interests and honor commitments to Asia-Pacific allies and partners.

Some experts have speculated that China might militarize a reef off the Philippine coast, the Scarborough Shoal, where a standoff with China prompted the Philippines to initiate the legal case in 2013. In the past two years, China has constructed artificial islands and placed military facilities on disputed features elsewhere in the South China Sea.

Willett said the ruling in the case would not resolve sovereignty issues, but could potentially narrow down the areas that are legitimately subject to dispute.

Denmark declined to comment on whether militarization of Scarborough Shoal by China would hurt U.S. national security interests, or invoke a U.S.-Philippine treaty, which calls for the allies to help defend each other if there is an armed attack on their armed forces, public vessels, aircraft or island territories under their jurisdiction in the Pacific.

"Scarborough Reef is a disputed feature that we don't recognize any countries sovereignty over. That said our treaty commitment to the Philippines is absolutely ironclad," said Willett, adding that occupying a currently unoccupied land feature or militarizing an occupied feature would be very dangerous and destabilizing.