President Donald Trump chose John Bolton, the former US ambassador to the United Nations, to be his new national security adviser.

The news sent tremors through the national security establishment, which is largely critical of Bolton.

The former Vice President Joe Biden once said he feared Bolton not because of Bolton's views but because of his effectiveness.

President Donald Trump's selection Thursday of John Bolton to be his national security adviser has alarmed much of the national security establishment.

Bolton, the former US ambassador to the United Nations, is a well-known conservative hawk who in recent years has railed against the US's Iran strategy, advocated a preemptive military strike on North Korea, and repeatedly defended the Bush administration's decision to invade Iraq.

Trump chose Bolton to replace H.R. McMaster, who resigned as national security adviser on Thursday after weeks of rumors about his looming departure.

But the former Vice President Joe Biden once indicated unease with Bolton that wasn't directly related to his foreign-policy goals but to his ability to achieve them.

In Bolton's 2007 book, "Surrender is Not an Option: Defending America at the United Nations," he described Biden's reaction to his 2005 confirmation hearing for the UN ambassador post, as noted Friday by the news website Axios.

Biden, who was then the ranking Democrat on the Senate Foreign Relations Committee, gave Bolton a brutally honest reason he disliked him, though he ultimately decided not to block his nomination.

"My problem with you, over the years, has been, you're too competent. I mean, I would rather you be stupid and not very effective," Biden said, according to Bolton.

Biden added that his opposition to Bolton was not about Bolton's "competence" and that he thought Bolton was "an honorable man" and "extremely competent."

Bolton clearly took the observations as a compliment — he wrote in his book that Biden's comments were the "high point" of his confirmation hearing.