Ukrainian and Russian officials will meet in Moscow on Thursday for talks to resolve a gas price dispute that has severely curtailed the flow of gas to all of southeastern Europe. All Russian gas supplies via Ukraine were halted Wednesday morning, with the two sides blaming each other for the cutbacks. Though most countries have reserves, the interruption could have grave effects, coming at a time of exceptionally cold temperatures. The European Union described the situation as unacceptable and called for the restoration of supplies.