The attacks eliminated checkpoints and facilities used by the al-Qaeda aligned militants to collect taxes to fund their violent campaign in Somalia, the statement on Sunday said.
"In addition to creating enhanced security, airstrikes help to disrupt al-Shabaab operations and the network while preventing future attacks by this terrorist group," said Marine Corps Maj. Gen. Gregg Olson, US Africa Command director of operations.
According to the statement, two airstrikes hit the Kunyow Barrow area, about 250 kilometres (155 miles) southwest of the capital, Mogadishu. â€¨â€¨Another strike was in the Awdeegle area, about 50 kilometers (31 miles) west of Mogadishu and a fourth was near Janaale, about 75 kilometres (46 miles) southwest of Mogadishu.
No civilians were injured or killed in the attacks, said the statement.
With these four airstrikes, the US military has carried out at least 16 such airstrikes this year in Somalia against al-Shabaab, which is widely considered the deadliest Islamist extremist group in Africa.
The United States has dramatically stepped up airstrikes against al-Shabaab since President Donald Trump took office.
The US carried out nearly 50 strikes in Somalia in 2018. â€¨â€¨Experts say it will take more than airstrikes to defeat the extremists, who continue to carry out deadly attacks in the Horn of Africa nation and neighbouring Kenya.â€¨â€¨On Friday, Somalia's oldest lawmaker was shot dead in an area north of Somalia's capital in an attack claimed by the al-Shabaab group.â€¨â€¨Osman Elmi Boqore, the country's oldest legislator estimated to be over 80, was shot dead by gunmen who pulled up near his car as he was being driven through Karan district, according to Somali police.