The speaker of Somalia's transitional parliament has welcomed the absence of gunmen at the airport when he returned to the capital, Mogadishu.
There are thousands of gunmen in Mogadishu
Mr Adan arrived with at least 20 MPs, intending to set up a rival administration to that of President Abdullahi Yusuf.
On Saturday, the warlords who control Mogadishu, and who back Mr Adan against Mr Yusuf, began merging their forces.
Somalia has been devastated by civil war and anarchy for 14 years.
The two-year peace process which led to the election of Mr Yusuf in Kenya had been seen as the most promising of 14 attempts to set up a national government.
But this optimism has been tempered by the recent splits and reports of a military build-up around the town of Baidoa.
The speaker said there had been a big difference since his last arrival in Mogadishu.
"I came here in February, but you were guarding me with dozens of battlewagons and hundreds of militamen. Today, I haven't set my eyes on even a single gunman," he said.
Three key Mogadishu warlords, who spent years fighting each other, have set up a joint force of some 650 men and sent them to training camps outside the capital, along with dozens of battle-wagons.
They said this would help bring peace to Mogadishu, home to thousands of gunmen.
But at the ceremony, one of the warlords, Mohammed Qanyare Affrah, who is also security minister, called for Somalis to be ready for a war against foreign peacekeepers.
The warlords and Mr Adan want the interim government to set up in the city when it leaves neighbouring Kenya.
But President Yusuf, who has little support in the capital, says Mogadishu remains too dangerous and wants to go to Baidoa and Jowhar instead.
That issue - and whether the government needs peacekeepers - have split the government.
Mr Adan may try to convene a meeting of MPs in Mogadishu to vote on the two matters.
More than 100 MPs who back Mr Adan have gathered in Mogadishu but they do not yet have a quorum of 138 of the 275-strong parliament.
Mr Adan was outraged when MPs who back Mr Yusuf last week voted to move to Baidoa and in favour of peacekeepers in the absence of him and some 100 MPs.
"It is totally unacceptable, dictatorial and is contrary to the spirit of reconciliation," he said.
Last week, the African Union voted in favour of sending some 1,700 troops to Somalia but said it would not send them unless it was safe and pointed out that it did not yet have the funds to deploy them.