As they informed us in a message, it is currently taking place attack DDoS on two government websites, which appear to be offline at the time of writing.
Sites are in the domains primeminister.gov.gr and startupgreece.gov.gr.
Both are subdomains of gov.gr where almost all government websites are hosted.
According to the Powerful Greek Army, the DDoS attack took place (and apparently continues to take place) on cooperation of the Greek hacking team with them @PhantomNations
Below you can see the screenshots shown by DDoS
In our question, why did PGA respond to these attacks:
To see how good protected they have such popular government sites, and they don't have any.
And a screenshot from startupgreece