The US is to officially recognise Somalia's government in Mogadishu after more than 20 years, says a US official.
The move could pave the way for US and international economic aid for the Horn of Africa nation.
Secretary of State Hillary Clinton will announce the news on Thursday at a meeting in Washington with Somali President Hassan Sheikh Mohamud.
He took office after the first vote of its kind since military dictator Mohamed Siad Barre was ousted in 1991.
Ghana News Headlines
For latest news in Ghana, visit Graphic Online news headlines page Ghana news page
"When the secretary meets with Hassan Sheikh tomorrow, she will exchange diplomatic notes with him and recognise the Somali government in Mogadishu for the first time in 20 years," Assistant Secretary of State Johnnie Carson told reporters.
'Major and significant'
The move recognised the new government's progress towards political stability and "breaking the back" of an al-Shabab insurgency, Mr Carson added.
Al-Shabab, a group aligned to al-Qaeda, had seized control of southern and central parts of Somalia before Ethiopian, Kenyan and African Union peacekeeping troops undertook a counter-offensive, supported by the US, to restore order.
The US never formally cut diplomatic ties with Somalia.
But the 1993 Black Hawk Down incident, when 18 American servicemen were killed after militia fighters shot two US military helicopters out of the sky, marked the country's descent into anarchy.
Mr Mohamud's government was fostered by a UN-backed and regionally supported effort to end nearly two decades of fighting.
Mrs Clinton is not expected to announce new aid measures for Somalia, which already receives US assistance for drought, famine and refugee relief.
But a senior US official told the Reuters news agency: "The fact that we recognise a government there will allow us to do things through USAid [US Agency for International Development] that we have not been able to do before.
"The fact that we recognise them as a legitimate government will allow the World Bank and the [International Monetary Fund] IMF to do things that they would not have been able to do before. This is major and it is significant."
Mr Mohamud has met World Bank and USAid officials on his trip to Washington.
The US does not currently have an embassy in Somalia, but officials indicated this could eventually follow Thursday's announcement.