Washington DC - President Donald Trump on Tuesday signed into law a bill designed to deepen US-Taiwan ties by forcing a review of how Washington engages with Taipei amid escalating threats from China.

The measure will force the State Department to conduct reviews of how the US engages with Taiwan every five years, with a focus on identifying and eliminating self-imposed limitations on trade and military assistance.

According to the bill, the State Department's reports to Congress "must describe how the guidance takes into account certain considerations, such as the sense of Congress that Taiwan is governed by a representative government peacefully constituted through free and fair elections."

In addition, the report will "identify opportunities and plans to lift self-imposed restrictions on relations with Taiwan."

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By committing to what is effectively a periodic review of the health of Taiwan's democracy, the bill intends to strengthen the US' relationship with Taiwan and shore up its ability to resist China.

"This is critical legislation that strengthens our relationship with Taiwan and sends the message that we stand strong against the Chinese Communist Party's dangerous efforts to dominate the region and spread their influence worldwide," wrote Representative Ann Wagner, who sponsored the bill, after it passed the Senate in November.

Trump's signature comes a week after he stepped in to calm a spat between Beijing and Tokyo over Taiwan's sovereignty, which China claims as its own.

Chinese President Xi Jinping and Trump touched on the issue of Taiwan during a phone call last week. Hours later, Trump was reportedly telling Japanese Prime Minister Sanae Takaichi not to provoke Beijing.

China has become increasingly threatening towards Taiwan over recent months, last week threatening to "crush" all foreign efforts to defend the self-governed island.