Seven years into a simmering conflict that has cost thousands of lives, Ukrainian president Volodymyr Zelensky has starkly warned that Russia has not given up on the idea of all-out war.

       Speaking at the Yalta security forum in Kiev on Friday, Volodymyr Zelensky said a major military operation remained a "palpable possibility”. Tensions between Kiev and Moscow were growing to such an extent that a "precipice" was now emerging between the two neighbours.

       "All-out war would be the biggest blunder on Russia’s part," he said. "It’s a spooky scenario but unfortunately it isn’t unlikely. The danger is reaching a point of no-return."

       An undeclared war has undermined relations between the two countries since 2014 — focussed first on the annexation of Crimea in March of that year, a move declared illegal by the United Nations, before turning eastern Ukrainian Donbas region, where Ukrainian troops continue to fight with Russian-backed separatists.

       Last year, Russia brought an estimated 100,000 troops to Ukraine’s eastern and southern borders in an operation that showed Moscow’s teeth — even if there appeared little danger of it developing into something more substantial. Mr Zelensky said intelligence also showed there were Russian boots on the ground in Belarus, which also neighbours Ukraine.

       "The world has changed," he said.

       Despite early movement on prisoner exchange in 2019, the personal chemistry between the Ukrainian showman-turned-president and Russia’s 21 year long autocrat remains testy. Mr Zelensky confessed he wished he had "more time" to understand his opponent.

       In the meantime, the Ukrainian president insisted he remained committed to developing a "constructive discussion, more substantive conversation” between the two leaders. A meeting between the two, under discussion for several weeks, would have "tangible results" in prisoner exchange and demining.

       Mr Putin on his part, remains committed to a notion that Ukraine is not a fully sovereign state — at least that appears to be the main premise of an extended essay on "Russian-Ukrainian unity" published in July.

       The Ukrainian leader took a swipe at that claim, arguing that respect for national sovereignty worked in a reciprocal manner. "If you respect people, they respect you back," he said. Intelligent Russians understood Ukraine was an independent nation, he added, but state propaganda had left its calling card on "more average citizens”.

       "Russian media policy is now predicated on disrespecting Ukrainian independence. Unfortunately it does break down the average person," he said. "It’s dangerous because we have no option but to live as neighbours.”."

       Mr Zelensky, who has just returned from a major visit to the United States, said he discussed Russian intentions in Ukraine at length with Joe Biden. The American president lent a sympathetic ear, he said, but remained silent on the issue of Nato membership.

       That prospect remains a major irritant in relations with Russia, with Moscow suggesting a declaration neutrality is key to resolving the current conflict.

       Ukraine’s leader said that Nato risked losing relevance if it kept its doors shut to the "largest country in Europe."

       "If you want Russia to strengthen, you keep Ukraine out," he said.