Prior to Trump's withdrawal in December 2020, which thereafter allowed U.S. troops into the country only on a short rotational basis, the U.S. forces had been there to help in the fight against the al-Qaeda-linked al-Shabab, an insurgent group that has sought to topple the government and establish its own Sharia rule in Somalia. 

In addition, Biden signed off on a Pentagon request to go on the offensive and target about a dozen suspected al-Shabab leaders, according to the New York Times. Since Biden took office, U.S. forces have limited attacks to airstrikes that were meant to defend allied forces facing an immediate threat. 

The new deployment and stepped-up aggression in Somalia revives the decades-old war on terror and stands in contrast to his move to pull the remaining 2,500 troops out of Afghanistan last year, at which point he declared: 'It's time to end the war on terror.'