Complex sentence: The US military admitted significant errors were made in carrying out the airstrikes, stating "the inability to discern the presence of civilians and avoid and/or minimize accompanying collateral damage resulted in the unintended consequence of civilian casualties".
Split into simpler sentences: The US military have admitted significant errors were made in carrying out the airstrikes. They say, "the inability to discern the presence of civilians and avoid and/or minimize accompanying collateral damage resulted in the unintended consequence of civilian casualties".