Sikorski spoke to reporters at UN headquarters in New York on the eve of a planned meeting between Trump and Ukraine's president.
"This is something President Trump can win, he can bring an honourable end to this war", Sikorski said, referring to legislation Trump signed last week allowing tariffs of up to 100 percent on countries buying Russian oil and gas. "I recall my public pledge that if he succeeds, I will personally nominate him for the Nobel Peace Prize".
Whether Trump actually uses the new sanctions power remains his call.
Sikorski said he would rather see Washington increase military support for Kyiv than continue pursuing ceasefire talks.
"I would put more emphasis on supporting Ukraine, and less on mediation attempts that have so far, unfortunately, failed", he said, arguing Russian President Vladimir Putin will only turn serious about negotiations once he concludes he cannot win the war at an acceptable cost.
Sikorski also brushed aside Trump's appeal for Ukraine to stop striking Russian oil refineries, a campaign that has pushed up diesel prices. He said Moscow would first need to say what it was willing to offer in exchange for any such halt.
On the threat to NATO, Sikorski said the alliance has detailed contingency plans but urged against underestimating Russian threats.
He described visiting Kyiv last week during a bombing raid and standing at a Polish border post where windows shook as Russian drones struck targets just 1.5 kilometres away, inside Ukraine.
"This really is not the moment to doubt the Russian threat, because the Russians are threatening us — and when Russia threatens us, that threat is credible", he said.
Asked about Slovak Prime Minister Robert Fico's suggestion that Bratislava might not honour its NATO obligations, Sikorski said such comments echoed views he has also heard from politicians at home.
On Trump's push for a fertiliser trade arrangement with Belarus, Sikorski said he was not familiar with the details but assumed both sides saw some mutual benefit in it.
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Source: PAP