U.S. President Donald Trump said he will talk to Russian President Vladimir Putin on Tuesday about ending the Ukrainian war.

Speaking to reporters on Air Force One on Sunday, Trump said “a lot of work” had been done over the weekend.

“We want to see if we can end this war,” Trump said. “Maybe we can, maybe we can’t, but I think it’s very likely we can.”

Asked what concessions are being considered during the ceasefire negotiations, Trump said the discussion will include land and power plants.

“I think there has been a lot of discussion on both sides, Ukraine and Russia,” he said.

“We are already talking about this, dividing certain assets.”

Trump’s comments were hours citing a senior Russian official in local media reports, saying any peace agreement would exclude NATO membership in Ukraine.

Russian Deputy Foreign Minister Alexander Grushko said in an interview with Russian media Izvestia that Moscow will need “Ironclad Security Security” to agree to the ceasefire.

“Ukraine’s lasting peace can only be achieved through the establishment of such as this assurance and regional security is strengthened overall. Ukraine and NATO countries do not accept the neutral status of alliance members should be part of these assurances.”

“In fact, this provision is precisely outlined in the draft of the above agreement. As for the discussion, they are not currently in progress because there is no negotiation.”

Earlier on Sunday, Trump’s special envoy Steve Witkoff said the two leaders planned to have “very good positive discussions” this week.

Washington hopes to convince both sides to agree to a proposal for a 30-day truce that broke out in talks in Jeddah, Saudi Arabia last week.

Although Ukrainian President Volodymyr Zelenskyy accepted the proposal, Putin has not yet committed his commitment to the plan, not just saying that he supports it in principle.

The Russian leader said last week that the plan will benefit mainly from Kiev as Russian forces gain, and that he has “serious problems” with the initiative.

Zelenskyy accused Moscow of not wanting to end the conflict and seeking to “improve their situation on the battlefield” before agreeing to a ceasefire.

Russia has driven Ukrainian troops to much of its Kursk region in recent weeks, where Kiev controlled approximately 1,300 square kilometers (500 square miles) of territory during its invasion in August.