U.S. Secretary of State Marco Rubio has said that the most difficult issue in negotiations to end Russia's war against Ukraine remains Russia's territorial claims to the Donetsk region. Answering senators' questions about the talks, Rubio said: "It's still a bridge we haven't crossed. "But it won't still be Steve and Jared [special envoy Steve Witkoff and the U.S. president's son-in-law Jared Kushner, who took part in the previous round of talks]. Rubio also noted that security guarantees for Ukraine have been agreed upon between Washington and Kyiv, while pointing to the Russian factor. As reported, the next round of trilateral talks involving the United States, Ukraine, and Russia is scheduled for February 1 in Abu Dhabi.