MOSCOW (Reuters) - Russia has sent troops to reinforce its border guards in Armenia and secure a peace settlement with Azerbaijan over Nagorno-Karabakh, the Federal Security Service head said on Friday. The deployment was made at the request of Armenia to maintain peace in Nagorno-Karabakh, FSS chief Alexander Bortnikov told Russian President Vladimir Putin at a conference via videolink. The mission involves 188 servicemen and military hardware. Russian border guards stayed in Armenia after the collapse of the Soviet Union under terms of a 1992 treaty between the two countries. Russia deployed nearly 2,000 peacekeepers to Nagorno-Karabakh in the last two weeks after a peace deal that halted six weeks of fighting between Azeri and ethnic Armenian forces, locking in place territorial gains by Azerbaijan.