The Ruen last reported its position off the coast of Somalia on Monday at 1810 GMT, according to data from ship tracking and maritime analytics provider MarineTraffic.
"The collective self-defense airstrike was conducted in the early morning hours of Aug. 26, in support of Somali National Army forces who were engaged by" al Shabaab, AFRICOM said in a statement.
The government has promised a second phase of the offensive that will go after al Shabaab in southern Somalia, the group's traditional heartland.
The bombing on Monday targeted the Jale Siyaad military academy.
In November, the group, which controls swathes of the country, attacked another hotel in Mogadishu, killing nine people.
The attack on the popular upmarket Pearl Restaurant, on the capital's Lido Beach, happened early on Friday evening.
Secretary of the Somali Defense Committee Ahmed Abdi Koshin says military offensive has 'successfully dislodged' the al-Qaeda-linked terror organization from many parts of the country.
The operation was approved by US President Joe Biden earlier this week and carried out within the past 24 hours.
The assailants rammed the military base in the village of Hawadley with a suicide car bomb and then opened fire.
Al-Shabab is a vicious organization that has worked with Al-Qaeda and other extremist groups and is often behind horrid terror attacks in Somalia.