The NATO Secretary General Jens Stoltenberg did not give any proofs that Russia allegedly violated the INF Treaty. The arguments of NATO members, proving Russia has violated the INF Treaty, are on the level of: “everything is in the social media”.
NATO stated several times and provided details how Russia has violated the INF Treaty, for instance in its statement by the North Atlantic Council on 1 February 2019 and earlier on 4 December 2018 in the statement by the NATO Foreign Ministers.
Back in November 2018 Jens Stoltenberg urged Russia “to provide details on Russia to make quick changes to comply in full with the 1987 Intermediate-Range Nuclear Forces (INF) treaty. Stoltenberg called on Russia to provide details about a new missile system the United States and other allies claim violates the accord”.
The NATO member – the US – also published a detailed report in February 2019 “Russian Compliance with the Intermediate Range Nuclear Forces (INF) Treaty: Background and Issues for Congress” by the Congressional Research Service where they stated how exactly Russia violated the treaty.
Read more disinformation cases about the INF Treaty here.