The Shabab have issued specific new threats against Americans in East Africa – and even in the United States – in recent months. Earlier this month, a senior CIA paramilitary officer was killed in action in Somalia. After a hiatus this year, Shabab fighters have stepped up a campaign of car bombs in Somalia, American counter-terrorism and intelligence officials said.

Security in Somalia has become increasingly tense over the past two years despite a concerted campaign of American drone strikes and US-backed ground attacks against Shabab fighters. This emerges from a report released on Wednesday by the Inspectors General of the Department of Defense and State and the US Agency for International Development.

“Despite longstanding ongoing pressure from Somali, US and international counter-terrorism, the terrorist threat in East Africa will not be affected,” the assessment concluded. “Shabab retains freedom of movement in many parts of southern Somalia and has demonstrated the ability and intent to attack outside the country, including targeting US interests.”

Several ominous signs suggest that the Shabab is attempting to extend its deadly operations well beyond a home base and attack Americans wherever possible – threats that have sparked 46 American drone strikes so far this year to try to destroy the conspirators wipe out. Last year there were 63 drone strikes, almost all of them against Shabab fighters, some against a branch of Islamic State.

In recent years the Shabab, which American intelligence analysts estimate to have 5,000 to 10,000 fighters, has lost many of the towns and villages it once controlled. Despite a record number of American drone strikes, the group has grown into a more nimble and deadly organization carrying out large-scale attacks against civilian and military targets in Somalia and neighboring countries.

“Overall, the withdrawal of US forces will give the Shabab a boost, improve its already advantageous position in the conflict, while weakening the government’s ability to counter or improve the group,” said Tricia Bacon, a Somali specialist at American University of Washington and former State Department counterterrorism analyst.

Even some of Mr Trump’s most determined Republican allies in Congress have warned of deep troop cuts in Somalia.