The navy is becoming more concerned about it's 1960s era EA-6 electronic warfare aircraft. In the 1990s, it was decided to retire the equally ancient air force EF-111 electronic warfare aircraft and depend solely on the EA-6. More money was allocated to rebuild EA-6s to keep them flying. But this has proved insufficient, particularly with the constant need for electronic warfare aircraft in the Balkans and over Iraq. The navy thinks it has made a strong case for having F-18Fs converted to EA-18 electronic warfare aircraft. But this will cost billions of dollars and the money has to start flowing soon, before more ageing EA-6's have to be retired because they are falling apart. An EA-18G aircraft is already in development and could be built and delivered to the troops by 2008. The EA-6's are expected to worn out by 2010-12. The new EA-18s would probably end up costing at least $100 million each. The air force, navy and marines need at least a hundred of these aircraft.