Recent tragic events have highlighted the importance of a robust military and especially of leadership — but also of the moral bankruptcy of moral relativism.

For a US secretary of state to suggest that Islamic terrorists had a “rationale” in slaughtering journalists is one of the low points of recent Western diplomacy, and it is indicative of a serious malaise.

For America to be embarrassed by its exceptionalism is itself exceptional and absolutely unacceptable.

In his great book “World Order,” Henry Kissinger writes: “America must retain its sense of direction.”

For America to have a sense of direction, two conditions are essential. First, a US leader must understand, be proud of and assert the American personality; an identity crisis isn’t a starting point for any journey.

Second, there must be clear goals informed by values and by a realization of the extraordinary potential of its people.

Around our country, there is a restless desire for revival. We see it in the presidential-primary process, which, apart from an interesting cast of characters, has articulated a deep distaste for the slow descent of our country.

And, importantly, there’s a yearning outside the country for American assertiveness and engagement.

As we’ve seen in Syria and in Ukraine and in the streets of Paris, without this country’s self-confident championing of that “human quest for freedom and humane values,” global affairs collapse into nightmare — the policy wasteland becomes fertile territory for terror.

We are all often struck by the exceptional qualities of America and by the exceptional and selfless influence America has exercised on the world.

We can idly and mildly joke, but if it were not for US intervention in the Pacific, we Australians would not speak with our distinctive drawl, but in the rather polite verb endings of Japanese — so let us not be PC, but frank: There is no way that Australia alone could have defended itself during the Second World War, heroic as Australian troops were.

In the 1950s, America saved the now prospering South Korea from the barbarity of Kim Il-sung. And that sacrifice and intervention provided the buffer that Japan needed to rise from the post-war ashes to be a great economy and a reliable ally.

One country, North Korea, is a heartless, ruthless personality cult that runs at the expense of its people, and the other country, South Korea, is a thriving democracy which has created companies that have improved lives around the world.

In the 1960s and 1970s, America intervened in Vietnam, an intervention that has been caricatured and distorted in the days since. The left seemed to be happy for the incarceration of millions, whether in Vietnam under Ho or in China under Mao. Why agonize over inhumanity when you could blithely celebrate yourself?

And in the 1980s, thanks to Ronald Reagan, America stood firm against the Soviet Union, and that very resolve led to its reform. It led to one Germany, not two. It allowed the Polish and the Hungarians and the Czechs and Slovaks to be independent, not political proxies. It recast Europe and emancipated millions.

And yet the left still cannot find the words to recognize Ronald Reagan. For the rest of the world, he changed it.

And in that very same era, the United States provided a stable background for the rise of China, which went from the impoverishment of mindless ideology to the magic of market forces, allowing hundreds of millions of people to escape from poverty through their own efforts.

America’s contributions to life itself are many and meaningful, from the mass production of antibiotics, to the banishing of polio, the treatment of HIV and the wonder of gene therapy and all that means for every disease.

We shouldn’t apologize for America; we should celebrate America. For the world as it might have been without America is a much, much lesser world.

Rupert Murdoch is executive chairman of News Corp. and 21st Century Fox and chairman of the New York Post. Excerpted from his remarks Monday night at the Hudson Institute.