By Yimou Lee and Ben Blanchard
TAIPEI (Reuters) -The United States has an "obligation" to fill its backlog of arms sales to Taiwan and there is a bipartisan effort to ensure this happens, a U.S. lawmaker said on Friday, as the island's defence ministry pushed for solutions from Washington.
Taiwan has since last year complained of delays to U.S. weapon deliveries, such as Stinger anti-aircraft missiles, as manufacturers turned supplies to Ukraine as it battles invading Russian forces. The issue has concerned some U.S. lawmakers and officials too.
The United States, like most countries, has no formal relations with Taiwan - which China claims as its own - but is Taipei's most important international supporter and arms supplier.
As Beijing has become more assertive, Taiwanese President Tsai Ing-wen has pushed defence reforms to make the military more mobile and harder to attack, seeking to turn the island into what U.S. officials call a "porcupine", and she has promoted self-reliance.
Meeting Tsai at the presidential office in Taipei, Rob Wittman, vice chairman of the House of Representatives Armed Services Committee, said Taiwan was making an "incredible effort" for its own defence, such as extending conscription.
"We have an obligation to make sure that we fill the backlog of foreign military sales that exist now between our countries," said Wittman, who also sits on the House select committee on China.
"I can tell you that members of the House on both sides of the aisle are focussed on making sure this $19 billion backlog in foreign military sales gets fulfilled."
Taiwan's defence ministry, in a report to parliament on its ongoing five-year planning review, a copy of which Reuters reviewed on Friday, calls for solutions to the delivery problems and noted the "increased threats from the Chinese communists".
The ministry said it will propose "multiple ways" to the United States to obtain weapons.
"For weapons and equipment that cannot be delivered on schedule, the United States is requested to take the initiative to contact other suppliers or allies to help our country obtain equipment for combat power immediately."
The ministry mapped out the weapons it aimed to bring into service, including the upgraded Patriot PAC-3 surface-to-air missiles and Lockheed Martin's High Mobility Artillery Rocket System, or HIMARS.
In its latest notification of arms sales last week, the United States approved a possible $500 million sale to Taiwan of infrared search and track systems for F-16 fighter jets, as well as other equipment.
Part of that is Taiwan's domestically developed missile programme, and the ministry's report said they would focus on long-range, precision weapons like the Wan Chien air-to-ground cruise missile.
The ministry said its "primary goal" is to improve asymmetric defence combat power by improving its long-range, precision, unmanned, manoeuvrable and artificial intelligence capabilities.
Wittman, accompanied by four other lawmakers from his Republican Party, offered reassurances of U.S. support.
"President Tsai, know that any, any hostile, unprovoked attack on Taiwan will result in a resolute reaction from the United States," he said.
While the United States has long followed a policy of "strategic ambiguity" on whether it would intervene militarily to protect Taiwan in the event of a Chinese attack, President Joe Biden, a Democrat, has said he would be willing to use force to defend Taiwan.
Tsai told the U.S. delegation that Taiwan looked forward to coordinating with the United States and other democratic partners to jointly defend regional stability and prosperity.
(Reporting by Ben Blanchard and Yimou Lee; Editing by Michael Perry and William Mallard)