Compare and contrast two terrorist groups

Compare and contrast two terrorist groups – one that was active primarily before the year 2000 and one that has been active primarily after the year 2000. Identify at least 3 similarities and 3 differences between the two groups. Additionally, compare the counterterrorism measures employed against each group, identifying at least one similarity and one difference. Explain why these counterterrorism measures may have been chosen and why they were effective or ineffective. Ensure you properly cite your sources.