Iran is slowly winding down stocks of oil stored on tankers close to its shores and the process is likely to take longer than Tehran had wanted, despite the lifting of international sanctions this month. The pace of sales taken from floating storage highlights the difficulties Iran is facing amid a global oil glut and other challenges such as the certification of its fleet. Iran parked over 40 million barrels of crude and condensate, a very light grade of crude, on 20 to 25 ships after Western sanctions were imposed over its nuclear program. The sanctions stopped most countries from buying Iranian oil in recent years. Most of the ships storing oil are run by Iranian tanker operator NITC.