The agency in charge of controlling the air space over Europe has warned airlines to exercise caution due to the possible launch of air strikes into Syria.
Eurocontrol said missiles could be used in the eastern Mediterranean sea within the next few days. As well as that, military equipment could cause intermittent disruption of radio navigation equipment.
US President Donald Trump has been discussing possible military action to punish Syria's President Bashar al Assad for a suspected poison gas attack on Saturday on a rebel-held town that had held out against government forces.
Trump cancelled a planned trip to South America later this week to focus instead on responding to the Syria incident.
Aviation regulators in countries including the US, the UK, France and Germany have previously issued warnings against airlines entering Syrian airspace, but the Eurocontrol statement included a broader area outside the Syrian airspace, which is controlled by Damascus.