Simplify the following text for a Grade 11 native English-speaking person.
Original: Hezbollah then launched more rockets into northern Israel and engaged the Israel Defense Forces ( IDF ) in guerrilla warfare from hardened positions .
Simplified: Over the years , the Hezbollah militia has fought a guerrilla war against the Israeli army ( IDF ) in Southern Lebanon . It also attacks Israel 's military positions by firing Katyusha rockets across Israel 's northern border .