Taiwan is to spend 17 billion Taiwan dollars (586 million US dollars) on upgrading its Indigenous Defence Fighter (IDF) warplanes, dpa quoted a newspaper as reporting Saturday. The Aerospace Industrial Development Corp (AIDC) said it would unveil the 70 air force jets which have been modified on Thursday, the United Daily News reported. Taiwan has 130 warplanes. Modifications would give the jets double the carrying capacity for Sky-Bow missiles to four. The Taiwan Air Force fleet also consists of 150 F16A/Bs and 60 Mirage 2000-5s. According to the report, Taiwan fast-tracked the upgrade after the United States refused to sell the island F16C/D jets or upgrade its F16A/Bs.