Can all non-combat units and missiles achieve "hardened" and "elite" levels?

Combat units achieve veteran, hardened and elite status after attacking or being attacked. Spies achieve veteran, hardened and elite status after successfully completing missions or after successfully defending against enemy diplomats/spies. What about non-combat units (e.g. settlers, workers, engineers, explorers, triremes, caravels, transports, AWACS, etc.) and missiles (cruise missile, nuclear)?

I know that it’s possible for some of these units to start with veteran status as a result of having a barrack, an airport, or a port facility in the city where the unit was built. However, I have never seen a some of these units with elite status. For example, I have never seen a trireme, AWACS, or a cruise missile with elite status. Do these non-combat units and missiles also get to achieve hardened and elite levels?