Since March 2004, when the Baltic states joined NATO, fighter jets of NATO members have been deployed on a rotational basis for the Baltic Air Policing mission at Šiauliai Airport in Lithuania to guard the Baltic airspace. Latvia participates in several NATO Centres of Excellence: Civil-Military Co-operation in the Netherlands, Cooperative Cyber Defence in Estonia and Energy Security in Lithuania. It plans to establish the NATO Strategic Communications Centre of Excellence in Riga.