The deal became the model for "open skies" agreements between Washington and more than 50 countries.

Washington has already reached open skies agreements with 12 countries in Europe.

Negotiations for an open skies agreement were scheduled to begin not later than March 25, 2010, according to a treaty between the two countries.

The Transportation Department signed open skies agreements with 10 other countries last year.

The two leaders expressed particular satisfaction with their open skies agreement, which covers the largest bilateral aviation market in the world.

That is because Britain does not have an open skies agreement with the United States.

All but Britain have open skies agreements with the United States.

Whether European countries would actually renounce existing open skies agreements is not clear.

Morocco and the EU signed an open skies agreement in late 2006.

Sixteen countries have open skies agreements, but eleven do not.