The US have violated the INF treaty first, back in 2014, when Washington began deploying Mk41 launchers in Europe, containing Tomahawk missiles. This is a direct INF violation.
Currently, these launchers have been dislocated in Romania and preparations are under way for their deployment in Poland and Japan.
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”.
The Romanian Defense Minister Mihai Fifor confirmed back in August 2018 the missile defense shield at Deveslu base, in the southern part of Romania, is not fitted with ballistic missiles.