Between them, GLCM and Pershing II made a lethal combination. GLCM missiles could be launched, undetected, followed 2 hours later by a Pershing strike, which would fly so quickly that it was possible no response could be made before the Pershings struck. Aside from presenting an course of action to NATO commanders in the event of war, it put the Kremlin leaders (in range of the GLCM and possibly the Pershing, even in Moscow) in a position of fearing a decapitating NATO first strike, which could have moved them toward a launch on warning policy as the only way to maintain deterrence.5 However, the USSR did have submarine-launched missiles (i.e. Golf and Hotel class SSBNs armed with R-27 Zyb and SS-N-5s) available during this time, so any fears of a decapitating first strike were not necessarily justified.[1]
Despite initial fears of greater instability, the deployment of GLCM ultimately caused Soviet leaders to enter into negotiations for, and finally signature of, the INF treaty. The recognition by Soviet leaders of the threat posed by the GLCM and Pershing II missiles made them far more inclined to agree to negotiate their own intermediate-range weapons, especially the SS-20, out of service, in exchange for the elimination of the threat posed by the GLCM and the Pershing II.6