US Secretary of State Michael Pompeo announced on Thursday that the US will be submitting notice of its withdrawal from the Treaty on Open Skies on Friday, May 22, 2020.

Secretary Pompeo noted reasons for the US withdraw were that Russia “has undermined [the] central confidence-building function of the Treaty – and has, in fact, fueled distrust and threats to our national security – making continued U.S. participation untenable.”

The Treaty on Open Skies, which was signed by 35 countries and took effect in 2002, permits each state-party to conduct unarmed reconnaissance flights with certain restrictions over the others’ entire territories to collect data on military forces and activities. In accordance with Article XV, the US withdraw will be effective no sooner than six months after the notice is given.

In a letter addressed to Pompeo, US Secretary of Defense Mark Esper, President Donald Trump, and two advisors, Representatives Eliot Engel and Adam Smith, argue that the US withdrawal comes in violation of Section 1234 of the Fiscal Year 2020 National Defense Authorization Act, which requires the president to notify Congress at least 120 days before the notice of intent to withdraw from the treaty is presented under Article XV.

Engel and Smith cautioned that, despite past Russian violations of the Treaty over Kaliningrad and occupied territories in Georgia, “the Treaty has brought unprecedented openness and transparency between participating countries and is highly valued by our allies and partners.”