Ukrainian President Volodymyr Zelenskyy says being admitted into NATO could end what he described as the “hot phase of the war” waged by Russia.

In an interview with Sky News aired on November 29, Zelenskyy suggested that he would be willing to consider a ceasefire if Ukraine’s unoccupied territories fell under NATO’s protection and the invitation to join the alliance recognized Ukraine’s international borders.

Russia annexed Ukraine’s Crimean Peninsula in 2014 and has been occupying 20% of Ukrainian territory since launching its full-scale invasion in February 2022.

“If we want to stop the hot phase of the war, we need to take under the NATO umbrella the territory of Ukraine that we have under our control,” Zelenskyy said, adding that the occupied eastern parts of the country could then be taken back “in a diplomatic way.”

This comes as U.S. President-elect Donald Trump has criticized the billions of dollars that the United States has poured into Ukraine since Russia launched its invasion.

Trump has also said he could end the war within 24 hours of retaking the White House, a statement that has been interpreted as meaning that Ukraine would have to surrender territory that Russia now occupies.

Earlier this week, Trump named Keith Kellogg, a retired army lieutenant general who has long served as a top adviser to Trump on defense issues, as his nominee to be special envoy for Ukraine and Russia.

Kellogg has advocated telling the Ukrainians that if they don’t come to the negotiating table, U.S. support would dry up, while telling Russian President Vladimir Putin that if he doesn’t come to the table, the United States would give the Ukrainians “everything they need to kill you in the field.”

For the past several months, Russia has been battering Ukrainian cities with increasingly heavy drone, missile and glide-bomb strikes, causing casualties and damaging energy infrastructure as the cold season settles in.

Earlier this month, a senior United Nations official, Rosemary DiCarlo, warned that Moscow’s targeting of Ukraine’s energy infrastructure could make this winter the “harshest since the start of the war” nearly three years ago.

Ukraine has launched several counterattacks since the administration of U.S. President Joe Biden, the top foreign supporter of Ukraine in its battle against Russia’s invasion, and Kyiv’s European allies authorized the use of long-range missiles against targets inside Russia.