“Our legislation is not going to be changed,” Ms. Hedegaard said.

Some European officials have suggested recently that parts of the new law could be suspended if there were clear progress this year toward establishing a global system. Those officials said such progress at the International Civil Aviation Organization, an arm of the United Nations, would have to be achieved by the end of the summer for the law to be suspended before the first payments are due on April 30, 2013.

On Friday, Ms. Hedegaard did not discuss the timeline for any possible modification of the European legislation. But any withdrawal of the law “must be the day where we actually have an agreement and it enters into force,” she said.

The move by Beijing earlier this month to bar its airlines from participating for now in the European system represents the most direct act of defiance yet. The United States Congress is considering similar measures.

The two-day conference in Moscow aims to adopt a resolution on the countermeasures and invite other countries to sign on.

Experts said the measures under discussion, if enforced, could disrupt the air industry.

The imposition of countermeasures would most likely be felt by consumers in the form of higher airfares and fewer options in terms of routes and frequency of flights to Europe, said John R. Byerly, a former United States deputy assistant secretary of state for transportation affairs who negotiated the 2007 Open Skies agreement with the European Union.

Airlines would lose many of the commercial incentives that were created by the easing of cross-border regulations achieved through bilateral air service agreements over the last few years, Mr. Byerly said.

“These rights are all very tenuous,” Mr. Byerly said of air service agreements, because governments typically had the power to terminate them with just a few months’ notice.