Photo taken on June 8, 2018 shows the Commander of the Greek Coast Guard and head of the Integrated Maritime Surveillance Service George Christianos stands in front of a coast-guard boat, at Marina Zeas in Athens, Greece. The search and rescue operations of thousands of migrants crossing the Aegean Sea, along with combating the illegal trade circuit are among the top priorities and challenges for the Greek Coast Guard, a Greek official told Xinhua here.