The shuttle system has become particularly important for Japan, which produces little crude oil domestically and must rely on imports. Shipping industry specialists said Greek and South Korean shipowners were among those reported to be operating shuttle tankers. The United States has been releasing about 1 million barrels a day from its Strategic Petroleum Reserve to stabilize prices and supply oil to Japan and Europe following the disruption at Hormuz. An export restriction might temporarily lower American prices but would reduce global supply and eventually push prices higher inside the United States as well. The conflict therefore threatens not only crude oil but also global LNG supplies.