AMERICAN president Donald Trump continues to surprise us. Just not in a good way.

After Trump’s recent dismissal by twitter of Secretary of State Rex Tillerson and the naming of hard-line sycophant CIA Director Mike Pompeo as his replacement, some US foreign policy observers thought perhaps the worst was over. While Tillerson hollowed out the State Department’s senior professional leadership and pushed for potentially crippling department budget cuts, his policy positions were generally sensible. He had seemed to be a counterweight to this president’s worst instincts in foreign policy.

But even though Tillerson’s reasonable voice was now gone, optimists were heartened that steady Jim Mattis remained as Secretary of Defence, and HR McMaster was still at the helm of the National Security Council. While there were rumours of a possible change in this key White House position, Trump had recently expressed his support for McMaster.

But over the weekend, one of the scariest figures in recent US history returned.

Trump announced he had dismissed McMaster and would install in his place John Bolton. Amid all the chaos, scandal, incompetence and carelessness of this Trump administration, Bolton has not occupied a prominent position in the public discourse. But even as Pompeo seems likely to play to Trump’s ignorant, impulsive instincts in international affairs, Bolton will probably be much more dangerous for the world.

The US national security adviser is the head of the National Security Council, a White House office charged with synthesising diverse perspectives from the many American foreign affairs bureaucracies and presenting to the president a list of cogent policy alternatives. The NSC director is expected to offer his thoughts as well, and these have often proven to be decisive as the American president makes his choices. Generally, however, the NSC directors have maintained relatively low-key public postures, in keeping with their great behind the scenes influence as policy arbiters.

While the NSC had existed long before his arrival as director under President Richard Nixon, Henry Kissinger was the NSC chief who has had the most visibility and direct personal influence. Quickly mastering the levers of bureaucratic power and influence in the Nixon White House, Harvard diplomatic historian Kissinger ingratiated himself with the embattled Nixon and became a trusted confidante who helped craft Nixon’s famous opening to China policy.

Now, John Bolton returns as a national security adviser very likely to achieve a public posture and position of influence to rival Kissinger’s. But while Kissinger was a widely respected diplomatic historian of prodigious output and acknowledged erudition, Bolton is a hard-line ideologue and documented bully. His appointment represents a dangerous turn for US foreign policy and further threatens America’s post-war position as the most likely curator of international peace and prosperity.

Sounding the first of what will be a cacophony of criticism of Trump’s latest personnel mistake, The Washington Post said of Bolton that “his record is that of rigid, bombastic ideologue with a history of bullying colleagues and twisting intelligence. His advocacy of extreme policies, including preventive war against North Korea and Iran, could lead (America) to catastrophe.”

Bolton first ingratiated himself with President George W Bush by visibly and volubly overseeing the vote recount in Palm Beach County, Florida after the 2000 presidential election. After a controversial and contentious stint in two State Department appointed positions on arms control and the UN, Bolton was rewarded with a nomination in 2005 as the American permanent representative to the United Nations.

Faced with reports of Bolton’s tempestuous and erratic behaviour and extreme foreign policy views, even the then Republican-controlled Senate refused to confirm Bolton’s nomination and he only received a recess appointment for a short time. Bolton nonetheless managed to offend and anger numerous colleagues. He remains one of the most vociferously passionate advocates for the American misadventure in the Iraq War. Perhaps even worse, Bolton once tried to pressure intelligence colleagues to support a spurious contention that Cuba possessed biological weapons, presumably to justify aggression.

Despite his public intemperance, Bolton is dangerous because he is a bright Yale Law School graduate who ably manipulates bureaucratic power. And there is no chance the US Senate can again block his appointment. The national security adviser is not subject to Senate confirmation.

For the moment, he’s here to stay.