The European Union and other trade powers are considering whether to hit at US imports in a move that could cause further strains within the global trading system, diplomats said over the weekend.
It could happen any time now that the deadline for the United States to conform to a World Trade Organisation (WTO) ruling that it must drop a practice widely supported in Congress has elapsed, they say.
Trade specialists outside the Geneva-based WTO said feeling against the practice - paying duties on imports deemed by a US court to be dumped to US firms making similar goods - is high.
"It seems that the EU at least is determined to act in the face of what it views as blatant delays by Washington since the Americans finally lost the WTO case early this year," said one Geneva envoy who preferred not to be named.
However, final decisions are unlikely to emerge in Brussels, Tokyo, Ottawa and other capitals until sometime in the New Year.
At issue is a Congressional amendment providing for diverting the duty payments from US government coffers, where they would normally go, to private firms. It was drawn up by Democratic Senator Robert Byrd nearly four years ago.
The crucial moment comes as the WTO is struggling to revive the stymied Doha Round talks for a new world trade treaty, and as the EU prepares to slap top-up tariffs totalling about $4 billion a year on US goods in another extended row.
The Byrd amendment went through Congress despite warnings from top trade officials in the previous Clinton administration that it was in clear violation of WTO rules.
The trade team appointed by then new President George W. Bush initially defended it stoutly, apparently seizing on a chance to prove the administration's dedication to defending "the interests of the American people".
But foreign anger sparked by the measure was reflected in the breadth of the coalition within the 146-nation WTO that quickly built up against it.
Apart from the 15-nation EU, this includes Canada, Mexico, Australia, Japan, South Korea, India, Indonesia, Thailand, Brazil and Chile.
The critics say the Byrd amendment encourages US manufacturers to launch self-serving anti-dumping cases against imports of competing goods.
In global trade practice, goods are deemed dumped if it can be shown that they are being exported at artificially low prices - perhaps to corner a market and undermine national producers.
In the United States, anti-dumping complaints from domestic companies are heard in the New York-based International Trade Court - a purely US body despite its name.
Under the Byrd amendment, critics say US firms stand to gain twice - getting the price of foreign rivals' goods forced higher and receiving the extra duties the importers pay.
WTO judges agreed that these payments amounted to illegal subsidies and said the practice should be abandoned. They had given Washington until December 27 to do this.
But there had been little sign that anything was going to happen on this front as payments still flowed, Congress - which would have to repeal the measure - is in recess, and most senators were insisting that the amendment must be kept.