A viral security message has been circulating on WhatsApp alarming the people of an elevated risk of terror attacks in Nigeria, specifically in Abuja. The targets include but are not limited to government buildings, places of worship, schools, markets, shopping malls, hotels, bars, restaurants, athletic gatherings, transport terminals, law enforcement facilities, and international organizations. The U.S. Embassy said it would offer reduced services until further notice.  

This claim is True. Here are our findings:

The U.S. Mission around the world periodically reissues and highlights best security practices for U.S. citizens residing in or visiting the country. These security alerts help citizens to stay informed. They can Register in the Smart Traveler Enrollment Program (STEP) to receive e-mails about travel and security information, and other messages important to American citizens. 

Conclusion: 

Our findings show that the US embassy did issue the security alert mail to update its citizens while also informing Nigerians why it is choosing to run reduced services till further notice. So the claim is True.