Russia warned U.S. lawmakers on Monday that any changes to the strategic nuclear arms limitation treaty signed by Presidents Barack Obama and Dmitry Medvedev in April could kill the pact.

Foreign Minister Sergei Lavrov’s warning, in an interview with the Interfax news agency, came with the White House pressing for a ratification vote on the New START treaty this week before the Senate breaks for Christmas…

Lavrov also played down the potential effects of failure to ratify New START, saying improved U.S.-Russian relations were not “directly dependent” on the pact, Interfax reported.