The fund, known as Security Action for Europe, is ultimately expected to generate 150 billion euros in defense investments. Countries have until November 30 to submit their requests, Reuters reported.
The Commission said the initial "strong interest" allowed it to prepare to raise funds on capital markets.
The countries that have so far shown interest are Belgium, Bulgaria, Czech Republic, Estonia, Greece, Spain, France, Croatia, Italy, Cyprus, Latvia, Lithuania, Hungary, Poland, Portugal, Romania, Slovakia and Finland.