The United States airstrikes that targeted Islamic State militants in northwestern Nigeria on Thursday marked a major escalation in an offensive that Nigeria's overstretched military has struggled with for years. U.S. President Donald Trump said on social media that the “powerful and deadly” strikes were carried out against Islamic State militants “targeting and viciously killing, primarily, innocent Christians.” Residents and security analysts have said Nigeria’s security crisis affects both Christians, predominant in the south, and Muslims, who are the majority in the north.