As the war between government forces and Russian-backed rebels continues in eastern Ukraine, a peace plan purportedly crafted by two associates of President Trump and a member of Ukraine’s parliament is causing an increasing backlash.

Ukrainian Prosecutor-General Yuriy Lutsenko said Tuesday that an investigation would be opened against lawmaker Andrei Artemenko on possible treason charges.

The New York Times reported Tuesday that Artemenko was suspected of conspiring with Russian officials to commit “subversive acts against Ukraine,” including pushing his proposal for a deal that would “legitimize the temporary occupation” of the Crimean peninsula.

Russia annexed Crimea in 2014 by force, soon after Ukraine’s Russia-friendly president fled the country in the wake of massive street protests. The U.S. and its allies in Europe have refused to recognize the Russian annexation, and have levied harsh sanctions against Russia in response.

Get Breaking News Delivered to Your Inbox

President Vladimir Putin’s seizure of part of a neighboring country also prompted NATO to deploy military hardware and thousands more troops -- including about 4,000 U.S. service members -- to countries on the edge of Moscow’s sphere of political influence in eastern Europe.

According to the Times, Artemenko flew into New York in January and met privately with Mr. Trump’s personal lawyer Michael Cohen and a Russian-American man named Felix Sater. Sater, said the Times, was a business partner of Mr. Trump’s who was tasked as recently as 2015 with scouting business opportunities for Mr. Trump in Russia.

Ukrainian lawmaker Andrei Artemenko speaks during an interview with Reuters at his office in Kiev, Ukraine, February 21, 2017. REUTERS

The Times reported that Artemenko crafted his plan, which calls for Ukrainians to vote on whether to lease Crimea to Russia for either 50 or 100 years, with Cohen and Slater, but the Trump associates’ role in the proposal is unconfirmed; other reports suggest the Ukrainian was essentially pitching the plan to the men in New York.

President Trump’s administration has yet to iterate a clear policy in relation to the Ukraine crisis, and there have been no official suggestions that the White House could reverse the Obama administration’s refusal to accept the annexation of Crimea.

Mr. Trump has strongly indicated a desire to mend relations with Moscow, while promising Urkaine’s leader that he will work to “restore peace” with Russia.

Mr. Trump has also appeared keen, however, to ease the U.S. sanctions against Moscow put in place after the annexation of Crimea. He told the Times of London in January that he would consider lifting the sanctions in return for a nuclear arms reduction deal.

Konstantin Kosachev, the Kremlin-connected chairman of the foreign affairs committee in the upper house of Russia’s parliament, made it clear Moscow wasn’t so anxious to get the sanctions lifted that they were prepared to “sacrifice something, especially in what concerns security.”

Russia is adamant that its annexation of the Ukrainian peninsula was legitimate and backed by the majority of the people who live there. Ukraine’s government and most of European nations -- like the Obama administration did -- view it as an illegal land-grab by Putin.