Speculation continues over a series of explosions that rocked one of Russia's largest airbases in Crimea.
The attack, at Saky, on the Black Sea coast, sent huge fireballs into the sky with experts suggesting it may have been a long-range drone strike, or even a missile strike, by Ukrainian forces.
A military airfield was the target in Saky, with it reportedly being a training base for Russian navy pilots and home to SU-24 naval attack aircraft which can carry cruise missiles.
Footage showed a series of fireballs erupting, two of them in quick succession, with one person reportedly killed and several more left injured.
Russia's defence ministry denied the base had been attacked, instead claiming a weapons store had caught fire.
However, Ukrainian officials have suggested the blasts could have been the work of saboteurs or their own Special Forces.
The level of damage points to it being some sort of weapon with the latest theory being that Ukraine has somehow managed to complete the development of its own Grim 2 tactical missile with a reported range of more than 300 miles.
Some experts think it may well have been something far simpler.
"Whatever the Ukrainians managed to hit the base with, whether it was saboteurs, my guess would be improvised UAVs with explosives/ launched ammunitions or a missile", said Justin Bronk, Senior Research Fellow for Airpower and Technology at defence and security thinktank RUSI.
"They hit fuel trucks or parked aircraft full of fuel. That then spread burning fuel over a significant area and then caught or then went into ammunition bunkers or fuel bunkers or engulfed aircraft parked that had weapons and fuel on board."