WASHINGTON (NYTIMES) - The Pentagon's Africa Command said on Tuesday (Oct 16) that it had carried out the deadliest attack against the Islamic extremist group Al-Shabaab in nearly a year, killing about 60 fighters in central Somalia.

The strike took place on Friday in the vicinity of Harardhere, about 480km north-east of Mogadishu, Somalia's capital, the military said in a statement.

Africa Command officials offered no other details except to say it did not kill or injure any civilians, suggesting the militants were in a camp or massing for an attack.

The strike came after a recent spate of attacks that Al-Shabaab has conducted against Somali security forces and their US advisers across the country.

On Sept 21, Al-Shabaab fighters attacked US and Somali troops 48km north-west of Kismayo. Ten days earlier, militants struck Somalia and US forces in Mubarak, in central Somalia, killing one Somali soldier.

"These sustained attacks demonstrate that Shabaab retains the ability to launch conventional offensives, in addition to its terrorist attack capability," said Mr Bill Roggio, editor of FDD's Long War Journal, a website run by the Foundation for Defence of Democracies that tracks military strikes against militant groups.

In its statement, the Africa Command said last week's strike was the deadliest against Al-Shabaab since an air strike against an Al-Shabaab camp north-west of Mogadishu on Nov 21 last year killed about 100 militants.

So far this year in Somalia, the United States has conducted 27 strikes, including by drone attacks, mostly against small numbers of Al-Shabaab fighters. That is on pace to surpass last year's attacks against the group.

The attacks by Al-Shabaab, Al-Qaeda's affiliate in East Africa, underscore the resilience of regional arms of Al-Qaeda and the Islamic State in Iraq and Syria (ISIS) group in places like Yemen, Libya, West Africa and Afghanistan.

Last weekend marked the anniversary of Al-Shabaab's deadliest attack, a truck bombing in Mogadishu that killed well over 500 people.

There are now roughly 500 US troops in Somalia; most of them are Special Operations forces, including Army Green Berets, Marine Raiders and Navy SEALs stationed at a small constellation of bases throughout the East African nation.

US military officials have expressed concern that the group is again growing - even after losing much of its territory in Somalia in recent years and being targeted by US drone strikes.