Final answer:
ISIS/ISIL became a threat in Iraq and Syria due to political instability, religious extremism, and regional conflicts.
Step-by-step explanation:
ISIS/ISIL became a threat in Iraq and Syria through a series of factors including political instability, religious extremism, and regional conflicts. In Iraq, the group took advantage of sectarian tensions and grievances against the government, seizing control of Sunni-dominated areas. In Syria, ISIS capitalized on the ongoing civil war and fought against both the government and other opposition groups. The group's use of violence, propaganda, and recruitment tactics also contributed to their growth and threat.