He has the status of a leader speaking from and living in a war zone, who has a proven willingness to be undiplomatic when he thinks it is necessary. That helps him achieve his objectives by setting himself apart from cautiously spoken politicians living in comfort and safety.
Drones and portable anti-aircraft and anti-tank weapons have been sent to Ukraine, but Zelenskyy has other specific requests.
"I've talked to the defenders of Mariupol," he said. "If only those who have been thinking for 31 days on how to hand over dozens of jets and tanks had 1 per cent of their courage."
On Saturday, the US said it would work with allies to transfer Soviet-made tanks to the Ukrainians for use in the east of the country, in Donbas. The Biden Administration has now provided about US$2.3 billion (NZ$3.3b) in military equipment to Ukraine.
Last Thursday, Zelenskyy spoke to Australia's parliament by video link and asked for armoured Bushmaster vehicles. Prime Minister Scott Morrison later told reporters the vehicles will be flown over on Boeing C-17 Globemaster transport planes.
New Zealand is providing non-lethal military equipment as well as financial aid.
Zelenskyy has a good grasp of the cards he can play for Ukraine's war effort, to get the expensive battle hardware the country needs while countries are willing to send it.
Ukraine isn't just Russia's target, it's the proxy front line between Nato and Russia and between a major authoritarian state and a democratic bloc. It's the place where President Vladimir Putin's aggression is being challenged, lest it threaten other nearby former Soviet states. Now Human Rights Watch says it has documented war crimes in Russian-controlled areas against civilians.
Zelenskyy has presented his arguments to countries in different ways. For Australia, he played on fears over China's aims in this region. However, it's possible China could be learning different lessons from Russia's difficulties.
He said: "The most terrible thing is that if we don't stop Russia now, if we don't hold Russia accountable, then some other countries of the world who are looking forward to similar wars against their neighbours will decide that such things are possible for them as well."
The Russian military is reportedly moving away from Ukraine's north to regroup in the Donbas area. Now would seem to be the time for Kyiv to exert more pressure to encourage Moscow to negotiate an exit. Ukraine appeared to have struck a fuel depot inside Russia on Friday.
On the other hand, the damage already inflicted to Ukraine's towns, cities and people is immense and the battering continues. Piling pressure on Putin could spark Russian escalation.
There have been signs of internal problems: Zelenskyy has removed two Ukrainian generals and has told his people not to collaborate with the invaders.
And the growing global economic problems caused by the war, on top of the pandemic, create their own pressures for Zelenskyy. So does the 24-hour news cycle.
An online fundraising campaign #StandupforUkraine will take place this weekend before a pledging summit for Ukraine.
He needs breakthroughs while sympathy, unity and resolve is there.
