Democratic lawmakers and national security experts have excoriated the White House's abandonment of the Open Skies Treaty.
The State Department announced it would submit its notice of withdrawal, which starts a 6-month countdown.
According to Business Insider, the 34-country treaty includes Russia, Ukraine, Canada, the Netherlands, and Norway.
These countries can conduct short-notice observational flights over other signatories to verify the status of each other's military forces.
However, there has been tension between the US and Russia over claims from both countries that the other is violating the treaty.
This decision weakens our national security interests, isolates the United States since the Treaty will continue without us, and abandons a useful tool to hold Russia accountable. Adam Smith (D-Wa.) and Rep. Jim Cooper (D-Tn.) House Armed Services Committee joint statement.