GENEVA (Reuters) - Disputes over U.S. tariffs and retaliatory moves by other states have sparked 12 requests for adjudication at the World Trade Organization, signalling an escalation in global trade tensions.

FILE PHOTO: World Trade Organization (WTO) headquarters in Geneva, Switzerland, July 26, 2018. REUTERS/Denis Balibouse/File Photo

The agenda for an Oct. 29 meeting of the WTO’s dispute settlement body on Friday confirmed the legal moves, which Reuters reported late on Thursday.

The dispute procedure begins with a 60-day window for talks to try to reach a settlement. The meeting agenda show that those talks have failed.

By asking for adjudication, the disputants are triggering litigation that could last years.

China, the European Union, Canada, Mexico, Norway, Russia and Turkey have all requested that the WTO set up a panel of adjudicators to judge the legality of steel and aluminium tariffs which U.S. President Donald Trump imposed in March.

In return, the United States has asked the WTO to adjudicate on tariffs imposed by Canada, China, Mexico and the European Union in response to those U.S. steel and aluminium tariffs.

It has also asked for adjudication in a separate case against China. Washington wants to impose tariffs on Beijing for its alleged failure to protect U.S. intellectual property rights.

Opponents of the 25 percent U.S. duty on steel imports and 10 percent on aluminium say they breach WTO rules. Washington says they are a national security matter, and therefore outside the WTO’s jurisdiction.

The wheels of WTO adjudication are slow, and particularly congested at the moment, with a record number of disputes working through the system.

The defendants in the disputes can reject the adjudication requests at the Oct. 29 meeting but would have to accept them at the November meeting.

Then a search for adjudicators will begin. Once they are appointed, which will take months more, they may take two years or more to report on the disputes.

The sides can then appeal, but the United States is threatening to cripple the WTO appeals system by blocking the appointment of judges.