TAIPEI, Oct 29 (Reuters) - The top U.S. representative in Taiwan, Sandra Oudkirk, said on Friday that the United States is committed to helping Taiwan defend itself. Speaking to reporters at her first news conference since assuming her post in July, she described U.S. relations with Taiwan as "rock-solid". "The United States has a commitment to help Taiwan provide for its self-defence," said Oudkirk, who heads the American Institute in Taiwan, the de facto U.S. embassy in the absence of formal diplomatic ties. Her remarks come as tension between Taiwan and China, which has not ruled out taking the democratically ruled island by force, has escalated in recent weeks. While the United States, like most countries, has no formal ties with the Chinese-claimed island, it is its most important international backer and main arms supplier. President Joe Biden"s administration has moved to restate that support, to the anger of Beijing. Washington is required by law to provide Taiwan with the means to defend itself but it has long followed a policy of "strategic ambiguity" on whether it would intervene militarily to protect Taiwan in the event of a Chinese attack. When asked if the United States would come to Taiwan"s defence if China attacked, Oudkirk said the policy towards Taiwan has been clear and remains unchanged, citing several U.S. laws governing its relations with Taiwan. A recent increase inChinese military exercises in Taiwan"s air defence identification zone are part of what Taipei views as stepped up military harassment by Beijing. The U.S. Secretary of State Antony Blinken on Tuesday urged all United Nations member states to support Taiwan"s "robust" participation in the U.N. system.