Washington, May 23 (IANS): Democrats have denounced US President Donald Trump's decision to withdraw from the Open Skies Treaty, saying it was illegal and demanded an explanation for the move.

In a letter on Friday to State Secretary Mike Pompeo and Defence Secretary Mark Esper, House Foreign Affairs Committee Chairman Eliot Engel and Armed Services Committee Chairman Adam Smith said that the withdrawal from the treaty without consultation with Congress violates Section 1234 of the Fiscal Year 2020 National Defense Authorization Act, reports Xinhua news agency.

"This provision of law stipulates that you must notify Congress not later than 120 days before the intent to withdraw from the treaty is presented to either treaty depository... To date, this requirement has not been fulfilled," the two Democrats said in the letter, demanding an explanation for this "intended illegal action".

Engel and Smith also said that they strongly oppose the withdrawal decision, which they believe would "specifically negatively impact US leadership in NATO and the transatlantic relationship with its allies and partners".

"It appears that short-sighted interests and partisan politics prevailed over reason and good foreign policy. This is a regrettable decision that will have lasting consequences," they added.

Trump on Thursday announced that he was withdrawing from the Open Skies Treaty, saying that "Russia didn't adhere to the treaty. Until they adhere we will pull out".

He also said that there was a "very good chance we'll reach a new agreement" with Russia.

Also on Thursday, Pompeo announced that the US would submit the notice of its decision to withdraw from the Open Skies Treaty to all other state parties on Friday, citing Russian non-compliance as a motivating factor for its decision.

The withdrawal would formally take place in six months, based on the treaty's withdrawal terms. Pompeo said Washington might reconsider its decision if Moscow returns to "full compliance with the Treaty".

The Russian Foreign Ministry said in a statement Friday that the country was open to dialogue with the US on the Open Skies Treaty, but only if it is based on equal rights and aimed at mutual consideration of interests and concerns.

The US and Russia have blamed each other for noncompliance with the treaty.

The Treaty on Open Skies, the implementation of which is monitored by the Vienna-based Organization on Security and Cooperation in Europe, has been in force since 2002 and allows its 34 signatory nations to fly over any part of one another's territory, photographing from the air, with the aim of ensuring that other countries or rivals were not preparing military attacks.

The official notification of Washington's withdrawal from the pact will be presented on Friday, which implies that within six months, which is by November 22, the US will no longer be a party to the agreement.

Over 1,500 Open Skies flights have been conducted since the deal entered into force in 2002, according to media reports.

Ten European nations on Friday issued a joint statement regretting the US' withdrawal.

"We regret the announcement by the government of the United States of its intention to withdraw from the Open Skies Treaty, although we share its concerns regarding the implementation of treaty provisions by Russia," said the Foreign Ministers of France, Germany, Belgium, Spain, Finland, Italy, Luxembourg, the Netherlands, Czech Republic, and Sweden in the statement.

"We will continue to implement the Open Skies Treaty which has obvious added value for our conventional arms control architecture and our common security," said the statement.

It was the latest in a string of moves by the Trump administration to withdraw from major international treaties.

Washington abandoned the Intermediate-Range Nuclear Forces Treaty with Moscow last year.

The pullout of the Open Skies Treaty further raised doubts over whether the Trump administration would extend the New Strategic Arms Reduction Treaty (New START), the last remaining nuclear arms control treaty in force between Washington and Moscow.

The New START, which expires next February, can be extended for at most five years with the consent of the two countries.

Russia has expressed willingness to extend the treaty, while the Trump administration has yet to officially reply.