With benchmark US crude prices crossing the $70 a barrel threshold, the shale drillers who helped upend global markets now face a new challenge. (Bloomberg) — For the oil industry, $70 offers a test of wills. With benchmark U.S. crude prices crossing the $70 a barrel threshold on Monday, the shale drillers who helped upend global markets now face a new challenge: Do they stick with promises of fiscal discipline and avoid new production? Or is it time to turn on the taps and reap the benefits of the highest crude prices in more than three years? U.S. oil traded at $70.37 a barrel at 6:55 a.m. in New York as traders braced for a re-imposition of U.S. sanctions on Middle East crude producer Iran. In quarterly earnings reports over the last two weeks, producers have modestly upped forecasts for oil and gas output but also mostly kept drilling […]