Sergei Skripal worked on the Trump dossier.
The US has pushed Russia to violate the INF Treaty. By deploying the Aegis missile defence system the US has compelled Moscow to develop the 9M729 missile system and violate the INF Treaty. The Aegis missile defence system, deployed by the US in Eastern Europe, violates the INF Treaty because it could also be used offensively, to launch cruise missiles. A Pentagon report states that with only minor modifications the Aegis system can be transformed from a defensive into an offensive system.
Recurring pro-Kremlin disinformation narrative about missile defence systems. The Aegis missile defence system (Aegis Ashore Ballistic Missile Defence System) is not in violation of the INF Treaty. The US State Department issued a detailed rebuttal of Russian allegations of US noncompliance with the INF Treaty in 2018. Moreover, in December 2017 NATO affirmed that the US is in full compliance with the INF Treaty, and that Russia possesses a new missile system that aroused “serious concerns”. In 2014 US President Obama accused Russia of testing an intermediate-range missile land-launched missile in violation of the INF Treaty. Since 2014 the US has repeatedly pressed Russia to return to compliance with its obligations under the Treaty. According to the US Department of State, Moscow seeks to deflect US and NATO concerns about the 9M729 by accusing the US of being the party in violation of the INF Treaty. The “Pentagon report” quoted in Sputnik article does not state that “with minor modifications the Aegis system can be transformed from a defensive into an offensive system”. The report deals with ballistic missile defence issues and does not discuss the transformation of defensive into offensive systems. There is no evidence that Russia developed the 9M729 missile system as a response to the US deployment of the Aegis missile defence system. Read more here, here and here.