KABUL, Afghanistan (AP) — U.S. Secretary of State John Kerry was engaged Saturday in a difficult round of shuttle diplomacy between Afghanistan's rival presidential candidates, hoping to secure a path out of the country's postelection crisis.

By Richard Balmforth and Natalia Zinets KIEV (Reuters) - Ukrainian war planes bombarded separatists along a broad front on Saturday, inflicting huge losses, Kiev said, after President Petro Poroshenko said "scores and hundreds" would be made to pay for a deadly missile attack on Ukrainian forces. In exchanges marking a sharp escalation in the three-month conflict, jets struck at the "epicenter" of the battle against rebels near the border with Russia, a military spokesman said. Warplanes also struck at targets near Donetsk, the east's main town where rebels have dug in, destroying a powerful fighter base near Dzerzhinsk, Andriy Lysenko, a spokesman for the "anti-terrorist operation" said. In an earlier air attack on a base near Perevalsk, north of Donetsk, two tanks, 10 armored vehicles and "about 500" rebel fighters were destroyed, he said.