Russia's Ministry of Foreign Affairs said on Wednesday the United States had yet to provide any evidence Moscow was in breach of a landmark arms control treaty, but said it was ready to keep discussing the matter with Washington.The United States delivered Russia a 60-day ultimatum on Tuesday to come clean about what Washington says is a violation of a 1987 nuclear arms control treaty, saying it would be forced to start a six-month process of withdrawal if nothing changed.Maria Zakharova, a spokeswoman for Russia's foreign ministry, told a briefing that the US embassy in Moscow had handed over a note on Tuesday evening saying Washington would quit the Intermediate-Range Nuclear Forces (INF) Treaty unless Russia began complying with it."These documents were received for further processing," said Zakharova. "In them once again there were groundless allegations about our alleged violation of this agreement. We have repeatedly said that this is conjecture. No proof (of our alleged violation) has been presented to us."