"Wherever you are, wherever you live, whatever you believe, that should make your blood run cold," he added.
Ardern has taken a stronger line on this conflict than it may appear from New Zealand. Australia, Europe, Britain, the US, Canada, and Japan - the countries that occupy our intellectual bandwidth - have taken tough stances on the war too, but these countries do not constitute "the world".
In the many hours of talking Ardern has done in her political career, she has never used language as strong as the language she is using against Russia. She called the Russian-backed referendums a "sham", she called the country a liar, and a lawbreaker.
Ardern gets time at the United Nations with the likes of Ukrainian Prime Minister Denys Shmyhal, not because Ukraine is critical of our efforts (though it doubtless wants us to do more), but because of what has been committed so far.
But Ardern also appears wary of falling into the trap of allowing Ukraine to dominate the other crises the United Nations should be discussing this week - climate change chief among them. There's a palpable frustration among countries in what UN-types call the "global south" (poorer countries) that Ukraine has sucked up precious political oxygen needed to tackle their pressing problems.
There's envy that the US, Britain and Europe are willing to do everything short of all-out war for Ukraine - weathering enormous domestic political problems because of the conflict's inflation contagion - when for decades now, these same countries have barely lifted a finger for the struggles of the global south, and in many cases have made their crises worse.
Ardern isn't blind to the gravity of Russia's threat - she confessed to rewriting part of her General Assembly speech, written nine days prior, in light of Russia's escalation this week - but she's keen to ensure other issues get oxygen too.
That context aside, Biden has had a blinder of a week.
His speech to the General Assembly would have been music to the ears of the likes of New Zealand - he even spoke earnestly about reforming the gridlocked Security Council, something New Zealand has wanted since it was established.
Biden also spoke about the United States' responsibility to curb its emissions and help other countries grapple with the effects of climate change - again, music to New Zealand's ears.
When you think Helen Clark had to manage eight years of a headstrong, violent Bush administration, and Bill English and Ardern had to manage Donald Trump - Ardern is lucky, despite all the other geopolitical headwinds she faces, that the current US administration is at least on the same page as New Zealand on many issues.
She is, wisely, not getting too comfortable with the arrangement. The fact that Putin has decided to paint himself a villain and Biden a hero, Ardern has no appetite to defrost (or re-frost) the Cold War.
When asked this question on Thursday, Ardern suggested this was a unique issue and batted away the suggestion she might become an involuntary cold warrior.
"The overwhelming views of everyone on this floor are captured by those early comments by President Zelenskyy, 'Ukraine wants peace, the world wants peace'.
"That is true, regardless of whether or not you are a nation state that took a clear position on the war in Ukraine or not… the question is then, how do we get there?" she said.
She walks the fine line between appropriate condemnation of an illegal war and ensuring she doesn't abet the unpicking of the already fragile ties binding the international community together.
Tensions between the US and China over Taiwan have already iced what was a breakthrough in the relationship on climate change, putting the world at risk.
Despite Biden's friendly overtures, many here can't put aside the feeling that the US is a fair-weather multilateralist.
Many of the leaders in the room remember the last occupant of the White House.
A scan of cable news channels in their hotel rooms will confirm that Biden has not cemented a new age of American co-operation however much he might wish to. Who knows who the president will be when addressing the general assembly in 2025?
The irony of America and Britain slamming Russia at the Security Council over an illegal war is not lost on anyone - and just in case, ex-British Prime Minister Tony Blair was spotted by the New Zealand press pack walking towards the United Nations' headquarters moments after the Security Council meeting had finished.
Blair was anxious to find legal justification for the Iraq war (his American ally, George W. Bush, had no such compunction). They came to the Security Council, seeking support for the invasion.
When it was not forthcoming, Blair joined the invasion anyway.
Ardern has been wise to keep at least a partial focus on climate change at the United Nations. She was warmly received by Pacific leaders when she made a surprise visit to a Pacific Islands' forum meeting, where she spoke at length about climate change.
Ardern has pulling power here, even as her star begins its inevitable descent at home. Her Christchurch Call event pulled big names: France's Emmanuel Macron (the Call's co-founder) and Spain's Pedro Sanchez.
No New Zealand prime minister will ever be at the vanguard of international relations, but Ardern appears to have won herself at least an itinerant seat at some of the top tables - the likes of Nato, the White House and the EU - while not deviating her focus from things like climate change, an issue that wins her friends in places such as the Pacific.
It's a difficult needle to thread, but with the world order unpicking itself around us, any thread that continues to tie nations together is one worth threading.