All year, an international row has raged over the European Union's decision to include all airlines using its airports in its Emissions Trading Scheme (ETS), designed to curb planet-warming pollution.

The European Union says it is protecting the environment. US opponents say it has breached sovereignty to try to fill its empty coffers. Both houses of the US Congress have passed rare blocking legislation yet to be signed by a president to counter the EU law.

This week, the UN's International Civil Aviation organization (ICAO), based in Montreal, is expected to take another stab at moving towards a negotiated solution.

The European Commission, the EU executive, has said it can change its law if the ICAO comes up with a robust global framework to limit airline emissions.

The problem is almost no-one thinks the ICAO can deliver in time, if at all, prompting warnings of rounds of retaliation.

Meanwhile, the airlines are campaigning for a dispute procedure, referred to as Article 84, which would stall the ICAO process, perhaps for years.

"We are spending our time pushing Congress to pass legislation that addresses this issue and urging the White House to move past diplomacy and toward legal action with an Article 84," Sean Kennedy, top lobbyist at A4A, told Reuters.

"There's no brinkmanship here. It's not a question of if an Article 84 is filed, it's just a question of when," he said.

ICAO dispute procedures, used on rare occasions when nations disagree over the body's practices, are extremely lengthy, in an organisation generally renowned for its slowness.

They have to be brought by member states, meaning A4A has to pressure the US Administration, f ollowing this week's presidential election. Whether Democrat or Republican it could be receptive on an issue that has won unusual bipartisan support in Washington.