LONDON—Oil fell below $100 a barrel in a volatile session on Wednesday, as it came under pressure from signs of progress in Russia-Ukraine peace talks and a closely-watched report that cut its forecast of world demand. Ukraine’s president said the positions of Ukraine and Russia were sounding more realistic, but time was needed. Russia’s foreign minister said some deals with Ukraine were close to being agreed. “Fears of a supply disruption have been tempered by tentative signs of progress in ceasefire talks between Russia and Ukraine,” said Stephen Brennock of oil broker PVM. “That said, an end to hostilities still seems like a long way off.” Brent crude fell 54 cents or 0.5 percent to $99.37 a barrel by 1037 GMT, having traded as high as $103.70 earlier. U.S. West Texas Intermediate (WTI) crude slipped 96 cents or 1 percent to $95.48. The price falls also followed the release of …