Complex sentence: Its 2006-2012 phase is however also attributed to Iranian proxy war with Israel in the region, which, however, has cut ties with Sunni Hamas movement due to the Syrian Civil War.
Split into simpler sentences: Its 2006-2012 phase is, however, also attributed to the Iranian proxy war with Israel in the region. Since 2012, Iran has cut ties with the Sunni Hamas movement due to the Syrian civil war.