"The timing of this ill-advised decision so close to our elections is distasteful," Hastings said on Thursday. "I urge the administration to reconsider and instead work with Congress to double down on supporting our allies and partners in Europe, and particularly working to secure the prompt extension of the New START Treaty".
Hastings said the Trump administration’s opposition to existing arms control agreements has undercut transparency and predictability in Europe at a time when US leadership is needed the most.
"The Open Skies Treaty has underpinned transatlantic security for decades, and has always enjoyed bipartisan support because of its contributions to US security and the security of US allies," Hastings said.
Earlier on Thursday, US President Donald Trump confirmed reports that his administration will withdraw the United States from the Open Skies Treaty, but added that the agreement could later be revived or replaced with a new version of the deal.
Later in the day, two US lawmakers, Senator Edward J. Markey and Congressman Jimmy Panetta, introduced legislation to prevent Trump and future US Presidents from withdrawing the nation from international treaties without first getting congressional approval.
On Thursday, US Secretary of State Mike Pompeo clarified that the US would leave the Open Skies Treaty within six months from Friday, but could reconsider the withdrawal if "Russia returns to full compliance" with the accord, while claiming that Russia had "weaponized the Treaty by making it into a tool of intimidation and threat".
Russian Foreign Ministry spokeswoman Maria Zakharova said that Moscow has not received official notification or clarification from the United States, noting that "public statements, to put it mildly, are not enough for drawing conclusions regarding the intentions of the US side".
The Open Skies Treaty, which entered into force in 2002, establishes a program of unarmed aerial surveillance flights over the entire territory of the states who are members of the accord.