Jamie Dettmer is opinion editor and a foreign affairs columnist at POLITICO Europe. Another round of U.S.-brokered Ukraine talks commence today in Abu Dhabi. The overall outlook remains no less bleak for Ukraine, as it inches toward the fourth anniversary of Russia’s war. Yet there are signs that what comes out of this week’s face-to-face negotiations may finally answer a key question: Is Russian President Vladimir Putin serious? On the eve of the planned two-day talks, Russia resumed its large-