Trump said on Thursday that Russia was not fully adhering to the Open Skies pact, which lets its nearly three-dozen signatory nations carry out short-notice flights over other country's territory to monitor any potential military operations.

The accord was designed to increase transparency and raise confidence between world powers, and advocates say Washington's exit could pose a security threat for Europe.

"We regret the announcement by the United States of its plan to pull out of the Open Skies treaty, even though we share the concerns about how the accord is being carried out by the Russian Federation," the countries said in a joint statement issued by France's foreign ministry.

The US accuses Russia of blocking flights from surveying military exercises, which are normally allowed under Open Skies.

NATO ambassadors are meeting on Friday to discuss the US withdrawal, due to take effect in six months' time.

Friday's statement was signed by France, Germany, Belgium, Spain, Finland, Italy, Luxembourg, the Netherlands, the Czech Republic and Sweden.

"The Open Skies treaty is a crucial element in the framework for reinforcing trust that has been created in the past decades, aimed at increasing transparency and security for the euro-Atlantic zone," it said.

The European nations said they would continue to talk to Russia "to resolve outstanding questions" including "unjustified restrictions" imposed on flights over Kaliningrad, a Russian exclave bordered by Poland and Lithuania.