U.S. negotiators worked on a proposed partial ceasefire in the 3-year-old conflict in Ukraine on Monday, meeting representatives from Russia one day after holding separate talks with a team from Kyiv. Senior Russian lawmaker Grigory Karasin, who took part in the Russia-U.S. talks in Riyadh, told Russian state news agency RIA Novosti that the conversation was “very interesting, difficult, but quite constructive.”