Mike Waltz, Mr. Trump's national security adviser, has been weighing several proposals in recent days to end the Russia-Ukraine conflict, two people familiar with the matter told CNN. While the specifics of the strategy are still being worked out, Mr. Trump's officials are likely to push for an early cease-fire to temporarily freeze the conflict while the two sides negotiate. The first is Mr. Kellogg's proposal that continued military assistance to Ukraine be conditional on Kiev's participation in peace talks with Russia and a "U.S. policy of seeking a cease-fire and a negotiated settlement of the conflict." Meanwhile, Ukraine's desire to join NATO would be "stalled" for an extended period of time in order to get Russia involved in the negotiations. The second option is a proposal backed by Rick Grenell, the former U.S. ambassador to Germany. Mr. Grenell has previously voiced support for the creation of "autonomous regions" within Ukraine, though he did not elaborate on what that would look like. Another idea would be to allow Russia to keep the areas it currently controls in return for Ukraine joining Nato, though few in Mr. Trump's circle seem willing to invite Ukraine into Nato anytime soon.