MOSCOW (Reuters) - Mikhail Gorbachev, the last Soviet leader, said on Thursday a landmark arms control treaty that helped end the Cold War was in peril and called for a summit between U.S. President Donald Trump and Russian President Vladimir Putin to save it.   Gorbachev, 86, said U.S.-Russia relations were in the throes of a  severe crisis  and that the treaty, which banned all Soviet and American short and intermediate-range land-based nuclear and conventional missiles, was now at serious risk. Gorbachev signed the pact - the Intermediate-range Nuclear Forces (INF) treaty - in 1987 along with then U.S. President Ronald Reagan in Washington. Russia, after the 1991 Soviet collapse, took on its obligations. Both sides have accused each other of violating the treaty in recent months however, stoking fears it might break down as U.S.-Russia ties continue to deteriorate amid allegations that Moscow interfered with the 2016 U.S. presidential election, something Russia flatly denies. Gorbachev, writing in government newspaper Rossiiskaya Gazeta, said the INF treaty was in danger and that Trump and Putin needed to meet and discuss the problems of nuclear disarmament and strategic stability.  It has turned out to be the most vulnerable link in the system of limiting and reducing weapons of mass destruction,  Gorbachev wrote of the landmark treaty.  If the system of curbing nuclear arms crumbles, and that is exactly what the collapse of the INF treaty can lead to, the consequences will be catastrophic.  The INF treaty required the United States and the Soviet Union to eliminate and forego all nuclear ground-launched ballistic and cruise missiles with a range of 500 to 5,500 Km, eliminating an entire category of weapon. Appealing to Trump and Putin, Gorbachev said he wanted to see a  fully-fledged  U.S.-Russia summit of the kind he took part in toward the end of the Cold War.  It s totally abnormal for the presidents of nuclear powers to meet somewhere  on the sidelines  (of an event) and that they have only met once,  Gorbachev wrote, referring to a meeting between Trump and Putin at the G-20 summit in Germany in July.      If the INF treaty could be saved, it would be a powerful signal for the whole world that the biggest nuclear powers understand their responsibility and take their obligations seriously,  wrote Gorbachev. 
Gorbachev, last Soviet leader, wants Trump-Putin summit to save arms pact