Complex sentence: Russian troops have started the process of demarcation (also known as "borderization") near South Ossetia-Georgia administrative boundary line and meanwhile gradually advancing the occupation line inside Georgia to enlarge the Russian-held territory.
Split into simpler sentences: Russian troops have started the process of demarcation near South Ossetia-Georgia administrative boundary line. The process is also known as "borderization" and involved gradually advancing the occupation line inside Georgia to enlarge the Russian-held territory.