Putin was speaking a day after French President Emmanuel Macron said 26 countries had pledged to provide postwar security guarantees to Ukraine, including an international force on land, sea and in the air.
Russia has long argued that one of its reasons for going to war in Ukraine was to prevent NATO admitting Kyiv as a member and placing its forces in Ukraine.
"Therefore, if some troops appear there, especially now, during military operations, we proceed from the fact that these will be legitimate targets for destruction," Putin told an economic forum in Vladivostok on Friday.
"And if decisions are reached that lead to peace, to long-term peace, then I simply do not see any sense in their presence on the territory of Ukraine, full stop."
Putin's comments highlighted the gulf between Moscow's position and that of Kyiv and its Western allies on the shape of future security guarantees for Ukraine under any agreement to end the three-and-a-half-year war.
Ukraine seeks robust backing from the West to protect it against any future attack. France and Britain, which co-chair a "coalition of the willing" in support of Ukraine, have signalled they are open to deploying troops to Ukraine after the war ends.
US President Donald Trump has said that Washington will not put troops on the ground but may provide other support such as air power.
Putin said security guarantees must be set in place for both Russia and Ukraine.
"I repeat once again, of course, Russia will implement these agreements. But, in any case, no one has discussed this with us at a serious level yet," he said.
Trump, who took office in January with a pledge to end the war quickly, hosted Putin for a summit in Alaska in August that failed to achieve any breakthrough.
Ukrainian President Volodymyr Zelenskiy has long been pushing for a direct meeting with Putin in order to make progress towards ending Europe's deadliest war for 80 years.
Putin said on Friday that he did not see much point in such a meeting because "it will be practically impossible to reach an agreement with the Ukrainian side on key issues".
However, he reiterated an offer he made earlier this week to host Zelenskiy for talks in Moscow.
"I said: I'm ready, please, come, we will definitely provide working conditions and security, a 100 per cent guarantee.
"But if they tell us: 'we want to meet with you, but you have to go somewhere else for this meeting', it seems to me that these are simply excessive requests on us."
Zelenskiy, without directly addressing the possibility of Moscow as a venue, said on Friday: "We are ready for any kind of meetings. But we don't feel that Putin is ready to end this war. He can speak but it's just words, and nobody trusts his words."
