Former US Secretary of State Mike Pompeo has slammed President Joe Biden for causing what he called a "decay of deterrence" as he voiced concerns over a "dangerous" security landscape marked by the authoritarian leaders of North Korea, China and Russia.

During an interview with Fox News on Tuesday, Pompeo, who served as the top US diplomat under then President Donald Trump from 2018-2021, took a swipe at Biden's foreign policy as Trump is seeking a second White House term in the November election.

"President Biden has allowed such an accelerated rate of decay of our deterrence that we had built up in the four years that President Trump and I were serving," he said, stressing "dictators" and "authoritarian regimes" do not fear the United States.

"A wide open southern border (and) a North Korean leader, a Chinese leader and a Russian leader who don't think that the US will stand up and defend its most sacred values. ... It's a place that is a very dangerous country here at home as well," he added.

Asked to comment on Chinese President Xi Jinping's recent remarks that his country's reunification with Taiwan was "inevitable," the former secretary stressed the need to oppose the idea of China taking the self-governing island democracy by force.

"We need to make clear ... we are not going to let him take over an independent and free Taiwan by force in the Pacific," he said. "It will be a very dangerous thing for all of us, whether that's the Hawaiian islands, Alaska, Guam and all of these places."

During his stint at the helm of the State Department, Pompeo engaged deeply in denuclearization negotiations with Pyongyang though the talks stalled following a no-deal Hanoi summit between Trump and North Korean leader Kim Jong-un in 2019. (Yonhap)