Thailand's petrochemical and plastic industry has petitioned the WTO over US using of a "zeroing" anti-dumping duty on Thai goods. This means that USA will assign "0? points to goods that are not dumped by Thai processors.
Normally, in zeroing, points are assigned to goods that are not dumped and points are taken away for goods that are dumped. Normally, points cancel themselves out, hence this results in no dumping. If the numbers remain below "6" then most countries do not impose dumping duty.
But, with the US assigning zero points instead of positive points to Thai goods that are not dumped, it could affect the balance of points. Thai goods are always on the dumping list, and could result in crossing the "6" point mark.