Since the devastating attack in Christchurch, there has been much discussion about the spread of xenophobic and anti-Muslim views in Australian media and politics. But this concern should also apply to the nation’s foreign affairs, where successive Australian leaders have put a distorted sense of diplomacy and realpolitik above principles and integrity.

In an age of growing illiberalism and rising national barriers, Australia has damaged its capacity to represent a voice of decency on the global stage. Part of the problem stems from its approach to asylum seekers, which has involved deliberately violating international law – a position that severely undermines its credibility when it speaks out against atrocities elsewhere. Australia’s unlawful approach – including indefinite offshore detention, payments to people smugglers, inhumane camps and its decision to cloak the entire process in secrecy – has been condemned by the United Nations and human rights groups, and praised by far-right leaders in Britain, France and the Netherlands.

Another factor that muffles Australia’s voice on the international stage is that its leaders have often found it difficult to speak candidly to the head of its main ally, the United States. This Washington servility is a particularly Australian problem, but its effects have become worse, now that the White House is occupied by a leader who takes silence as a tacit endorsement of his racism, misogyny, illiberalism and Islamophobia.

Australian leaders have repeatedly failed to understand the nature and significance of the US alliance: it is a far-reaching security pact built around a shared strategic outlook and will endure as long as both countries believe it is mutually beneficial. Its weight and value may change according to circumstances such as, say, the rise of China as a regional power, but do not hinge on whether John Howard spent a weekend at George W. Bush’s Texan ranch.

Australian leaders believe they must pander to Donald Trump, despite his bile. Discussing Trump’s populism, which has involved denouncing immigrants and appealing to a predominantly white voter base, Scott Morrison last year praised the president, saying they shared an understanding of the concerns of those alienated by globalism. “I think we both get it,” he told The New York Times’s Maureen Dowd.

Malcolm Turnbull went further. In a conversation with Trump, as the president was introducing his ban on travellers from several Muslim-majority nations from entering the US, Turnbull told him: “We are very much of the same mind.” Turnbull continued: “It is very interesting to know how you prioritise the minorities in your executive order. This is exactly what we have done with the program to bring in 12,000 Syrian refugees, 90 per cent of which will be Christians.” Of course, we only know about this conversation because a transcript was leaked to The Washington Post. We don’t know what these and other Australian leaders have told Trump and his predecessors privately.

Turnbull was trying to persuade Trump to stand by a deal to take asylum seekers from Australia’s offshore camps. He told Trump the asylum seekers were not “bad people” and that the policy was aimed at stopping people smugglers bringing more of them by boat. But Trump, unsurprisingly, misunderstood, seeing the policy as an attempt to keep out foreigners. “That is a good idea,” Trump said. “We should do that too. You are worse than I am.”

During successive visits to Washington, Turnbull congratulated Trump on passing a bill aimed at undoing public healthcare, but declined to comment on gun laws after a shooting massacre at a school in Florida.  “It’s a completely different context historically, legally and so forth,” he said. The former prime minister’s approach has long been the norm for Australian leaders in their relations with US presidents. But there are different ways to talk to leaders such as Trump that do not jeopardise the alliance, yet preserve Australia’s dignity and help to ensure the country does not encourage views or conduct that is reprehensible.

After Christchurch, Trump called New Zealand’s prime minister, Jacinda Ardern, to ask what assistance the US could provide. Ardern told him: “Sympathy and love for all Muslim communities.” Shortly after, Trump tweeted: “We love you New Zealand!”