John Bolton, the pro-war and former United Nations ambassador under George W Bush, is a likely contender for Donald Trump’s next secretary of state.

The anti-Iran and anti-Russia hawk failed to secure a longer term as UN ambassador after Democrats banded together to prevent him.

He served less than two years, during which there was a rise in anti-US sentiment around the world.

In his latest blog, Mr Bolton named the five "gravest" threats to US security abroad: Isis, Iran, North Korea, Russia and China.

He also said the priority for the US government should be to quell the "proliferation" of nuclear and chemical weapons across the Middle East.

"Destroying ISIS should certainly be a priority, but not Obama's approach, which actually strengthens Iran's hand at the expense of America's traditional allies in the region, Israel and Arab states alike," he wrote.

Former New York City mayor Rudy Giuliani is also speculated to be on the list for the coveted position of secretary of state, after he said he would not be attorney general.

Mr Trump said in August that Mr Bolton was one of his go-to experts on foreign security, and described him as a "tough cookie".

But selecting Mr Bolton for the top job would break Mr Trump’s pledge to work peacefully with other countries, and would cast doubt over his seemingly positive relationship with Russian leader Vladimir Putin.

In 2014, Mr Bolton speculated that Russia was responsible for the downing of a Malaysian plane over Ukraine.

He told Fox News: "I think we’ve got to begin to treat Russia like the adversary that Putin is currently demonstrating it to be."

This year, Mr Bolton vocally opposed any attempts to "legitimise" Russia’s efforts to defeat Isis in Syria, contrary to Mr Trump who proposed Russia and Syria should be left alone to "fight it out".