West Texas Intermediate and Brent crudes charted the biggest weekly gains this year as Islamist fighters extended their advance in Iraq , triggering concern of a return to civil war. Futures in New York climbed 4.1 percent this week while they added 4.4 percent in London. Government forces in Iraq, OPEC’s second-biggest oil producer, are seeking to dislodge Islamist militants from cities north of Baghdad after they overran army positions in Mosul this week. U.S. President Barack Obama said yesterday he won’t rule out using airstrikes to help the government. “Prices have jumped to nine-month highs as the upsurge of violence in Iraq has raised additional risk of supply disruption,” said Gene McGillian , an analyst and broker at Tradition Energy in Stamford, Connecticut. “The situation in Iraq is going to continue to guide the market for a while.” WTI for July delivery rose 38 cents today, or 0.4 […]