In a daring missile attack that sent shockwaves through the region, Ukraine targeted the headquarters of Russia’s Black Sea Fleet in Crimea on Friday.

The attack, which resulted in a serviceman’s mysterious disappearance and extensive damage to the main building, has further raised tensions between the two warring nations. Here’s what we know so far.

The Russian Defense Ministry initially reported one servicemember killed in the attack but later issued a subsequent statement indicating that the individual was missing.

The incident unfolded in the port city of Sevastopol, located on the Crimean Peninsula, a region that Russia illegally annexed from Ukraine in 2014.