UP to 12 fighter-bombers are to be part of a massive security operation for President Barack Obama's visit to Darwin on Thursday. Soldiers, federal and Territory police, and up to 500 US secret service agents will also keep the President safe. The Australian Defence Department said the F/A-18 Hornets would be an ``important component'' of the security arrangements. The President will lay a wreath at the USS Peary memorial in Darwin and talk to troops at the RAAF base. A US official said: ``The President and Prime Minister Gillard together will address Australian troops in Darwin.'