Israel tracking Russian troop movements in Syrian port?

This one is surreal. A report in the Sunday Times of London (where else?) claims that IDF's Shayetet 13 planted listening devices in rocks in the Syrian port of Tartus to track the movements of Russian troops.

According to the report, the materials were
planted under cover of darkness by the IDF’s Shayetet 13 naval
commandos, who spent several hours on the island installing the
equipment