In the Middle East, Israel has threatened military action against Syria and Iran. Saudi Arabia is also challenging Iran, to curb the country’s growing influence in the region.

In Egypt, the president, Abdel Fattahel-Sisi, has been tightening his grip on power, using the military to crack down on political opponents. He has just secured a bogus electoral victory. (Will Arab soldiers never learn that dictatorship increases Islamist fundamentalism and promotes instability?)

But this trend is not limited to the Middle East. Russian president, Vladimir Putin, has just sailed to his own guaranteed electoral victory, thanks partly to his use of the security services, and their friends in the Russian mafia, to eliminate any potential threat.

But the Kremlin is not satisfied with damaging Russia’s own polity with plutocratic gangsterism; it is also working to undermine democratic processes elsewhere.

Then there is China, where the president, Xi Jinping, has become the most dominant leader since Mao Zedong.

Now that the presidential term limits introduced by Deng Xiaoping to insulate the country against another dictatorship have been eliminated, the future of the communist dynasty rests on the shoulders of one supreme leader.

Even the US, the country that we associated with leadership of the free world, is facing bleak prospects.

Under leaders such as Harry Truman, Dwight Eisenhower, George H.W. Bush, John F. Kennedy, and Barack Obama, the country shaped the international system for the better.

Now, Donald Trump — ignorant, prejudiced, deceitful, mendacious, and amoral — is destroying that legacy. When Trump was elected, some suggested that he would rise to the occasion. Leaving the campaign trail behind, cooler heads and wiser advisers would constrain him, and he would learn how the US government works. That optimism was sorely misplaced.

Well into his second year in office, Trump is behaving worse than his record indicated he would, unceremoniously tossing aside advisers and other officials.

Most recently, he replaced Rex Tillerson — frequently viewed as one of the ‘adults in the room’, who would protect the US and the world from Trump’s worst instincts — with the combative former CIA director, Mike Pompeo, as secretary of state.

Even worse, Trump has replaced former national security adviser, General H.R. McMaster, with John Bolton — the foreign-policy official with perhaps the most dangerous views in the entire Western world. Bolton is an ‘America First’ devotee and a bureaucratic thug, adept at eliminating rivals.

More dangerous, Bolton is the ultimate foreign-policy hardliner, the hawk to end all hawks. Among the loudest cheerleaders for the US invasion of Iraq, Bolton seems to think that every problem merits a military response.

The current conflicts with North Korea (he has called for preemptive military action) and Iran (he has repeatedly proposed regime change by force) are no exceptions. Between Bolton and Pompeo, the chances that the US will withdraw from the Iran nuclear deal, and reimpose sanctions on that country, have increased.

The mere expectation of that outcome has driven up oil prices — another gift from Trump to Putin.

Things are not much better on the economic-policy front. Now that Trump has filled his economic team with nationalists, his long-promised trade protectionism is becoming a reality.

To be sure, Trump is not wrong to confront China over intellectual-property theft and flagrant mercantilism.

What is wrong is his approach: Instead of recruiting allies such as Japan and the EU to put pressure on China, he has angered friend and foe alike, with unilateral tariffs and other ill-advised barriers, risking a trade war that would hurt everyone.

Trump’s behaviour has rapidly eroded US global leadership. His disregard for liberal democratic values has weakened the institutional pillars of the world order that the US itself had long-championed.

The only way to arrest this decline is for the world’s other liberal democracies — in Europe, Asia, and the Commonwealth — to take action. These countries must urgently defend free trade and open markets.

Working with the World Trade Organization, they should mount a co-ordinated effort to push back against abuses by both China and the US.

These countries should fortify the international rule of law — a concept that makes Bolton reach for his gun — by strengthening the United Nations, the World Bank, and the International Monetary Fund.

This means upholding the principles that have supported peace and prosperity since the 1950s, including by backing the Iran nuclear deal, as long as the country continues to hold up its end of the bargain, and pursuing a peaceful resolution to the North Korea crisis.

As Trump and his team devise one damaging policy after another, the world’s other democracies must respond. Only then can the international community hope to hold on, until responsible American leadership returns.

Chris Patten, the last British governor of Hong Kong and a former EU commissioner for external affairs, is chancellor of the University of Oxford.