Zelenskiy was in London on Friday for talks with two dozen European leaders who have pledged military help to shield his country from future Russian aggression if a ceasefire stops the more than three-year war.
The meeting hosted by British Prime Minister Keir Starmer aimed to step up pressure on Russian President Vladimir Putin, adding momentum to recent measures that have included a new round of sanctions from the United States and European countries on Russia's vital oil and gas export earnings.
The talks also addressed ways of helping protect Ukraine's power grid from Russia's almost daily drone and missiles attacks as winter approaches, enhancing Ukrainian air defences, and supplying Kyiv with longer-range missiles that can strike deep inside Russia.
Zelenskiy has urged the US to send Tomahawk missiles, an idea US President Donald Trump has flirted with.
The Ukrainian leader said Trump's decision this week to impose oil sanctions was "a big step", adding "we have to apply pressure not only to Rosneft and Lukoil, but to all Russian oil companies".
"Besides, we are carrying out our own campaign of pressure with drones and missiles specifically targeting the Russian oil sector," he said at a news conference at the Foreign Office in London.
Putin has so far resisted efforts to push him into negotiating a peace settlement with Zelenskiy and has argued that the motives for Russia's all-out invasion of its smaller neighbour are legitimate. Russia has also been adept at finding loopholes in Western sanctions.
Putin's rigid stance has exasperated Western leaders.
"He's rejected the opportunity for talks once again, instead making ludicrous demands for Ukrainian land, which he could not and has not taken by force," Starmer said at a news conference alongside Zelenskiy and several other European leaders.
"Of course, that is a complete non-starter."
NATO Secretary-General Mark Rutte said Putin's goals remain unchanged but he "is running out of money, troops and ideas."
Details of the potential future "reassurance force" are scant, and the London meeting seeks to further develop the idea — even though any peace agreement appears at the moment to be only a distant possibility.
The force is likely to consist of air and naval support rather than Western troops deployed in Ukraine, according to officials. UK Defence Secretary John Healey says it would be "a force to help secure the skies, secure the seas, a force to help train Ukrainian forces to defend their nation".
The war has shown no sign of subsiding, as a front-line war of attrition kills thousands of soldiers on both sides while drone and missile barrages cause damage in rear areas.
The Russian Defence Ministry claimed Friday that over the past week its forces have captured 10 Ukrainian villages.
The Defence Ministry also said its forces downed 111 Ukrainian drones over several regions overnight, with debris causing damage to homes and infrastructure.
Meanwhile, Ukrainian authorities said Russian artillery struck a residential block in the southeastern city of Kherson on Friday, killing two people and injuring 22 others, including a 16-year-old.
Russian planes also dropped at least five powerful glide bombs on the northeastern city of Kharkiv - injuring six people and damaging homes, according to Kharkiv Mayor Ihor Terekhov; and more on Ukraine's southern Odesa region.
