President Barack Obama has cut off US imports of charcoal from Somalia, hoping to starve militant Islamist group al-Shabab of resources.
The step is one of several in an executive order Mr Obama issued on Friday targeting Al-Shabab, whose attacks have helped keep Somalia without a fully-functioning government for more than two decades.
Other measures include freezing the assets of individuals accused of threatening the peace in Somalia, obstructing humanitarian efforts and attacking African Union peacekeeping forces.
Mr Obama's order says Somalia's charcoal exports "generate significant revenue" for al-Shabab militants.
In a letter to the US Congress, he says the steps aim to combat corruption, piracy and a deteriorating security situation in the east African country.