Al Shabaab have significantly increased their attacks in Mogadishu, with explosions in the Somali capital occurring on an almost daily basis over the past two months
This upsurge in bombings and mortar attacks may be an indirect result of the stepped-up US air war on Shabaab targets in rural Somalia, the United Nations secretary general said in a report.
"Air strikes were deemed to have degraded Al Shabaab's operational capability and freedom of movement," Secretary General Antonio Guterres told the UN Security Council.
"They have also led, however, to increased Al Shabaab movement into urban centres, in particular Mogadishu, where their forces are less likely to be targeted from the air."
The greater frequency of mortar attacks is accompanied by "Al Shabaab's improved capacity to hit strategic targets with precision and accuracy," Mr Guterres added.
His report coincided with a Security Council session on the UN Assistance Mission in Somalia (Unsom) that included some positive assessments of the country's efforts to enhance stability.
The meeting also highlighted differing views on the part of the United States and Somalia in regard to UN-backed restrictions on arms imports by the Somali government.
Abukar Dahir Osman, Somalia's UN ambassador, told the Security Council that significant gains have been made against Al Shabaab in recent weeks.
He added, however, that progress is difficult to sustain "with one hand tied behind our back."
Mr Osman expressed regret over provisions in the longstanding arms embargo that apply to the Somali government.
Initially adopted in 1992, the embargo was subsequently amended to allow some arms to reach Somali security forces but under condition that a UN panel of experts must be notified in advance of such transfers.
Jonathan Cohen, the acting US ambassador to the UN, implied in remarks to the Security Council that the Somali government may not be abiding by those provisions.
"Somalia appears to believe that the Security Council will eventually lift the sanctions despite a lack of engagement with the panel," Mr Cohen said.
"The United States will not support this view that does nothing to address the problems the sanctions regime was designed to address and indeed undermines the actions of the Security Council."