CAIRO - Egypt's President Abdel Fattah al-Sisi on Wednesday ordered his military command to use all force necessary to secure the Sinai peninsula within the next three months following a militant attack on a mosque that killed more than 300 people. 'It is your responsibility to secure and stabilize Sinai within the next three months,' Sisi said addressing his new chief of staff in a speech, without giving details on any operations. 'You can use all brute force necessary.' No group has claimed responsibility for Friday's mosque attack, but Egyptian forces have been battling a stubborn Islamic State affiliate in the North Sinai for more than three years and militants have killed hundreds of police and soldiers.