Ukraine still needs air-defense interceptors, the missiles fired upward to destroy incoming rockets and drones before they reach the ground. Greece holds a stockpile of them, attached to a relatively modern S-300 variant called the PMU-1 that Athens acquired in the late 1990s, and those weapons could help Ukraine's defenses. They will not be going there.
The PMU-1 is one variant within the S-300 family, a surface-to-air missile system with Soviet-era origins. Greece picked up its version, along with the interceptor missiles that go with it, during the late 1990s. That timing places the hardware on the more recent end of the S-300 spectrum, which is why it is worth noting at all.
The core fact is simple. Greece still possesses the system. It still holds the interceptor stockpiles. Ukraine still needs both. The gap between Greek capability and Greek willingness to transfer remains open, and for now the PMU-1 and its missiles are staying in Greek hands.