BBC Middle East analyst
The leader of Iraq's main Shi'ite opposition group, Ayatollah Mohammad-Baqer Hakim, has said he is going to return home after living in exile in neighbouring Iran for more than two decades.
Iraqi Shi'ites are concerned about their role in a post-Saddam Iraq
He is the head of the Iranian-based Supreme Council for the Islamic Revolution of Iraq, which is believed to have about 15,000 fighters.
Since the beginning of the US-led war in Iraq, Washington has repeatedly warned both Ayatollah Hakim's group and their Iranian hosts not to intervene in the war in Iraq.
Ayatollah Hakim's spokesman insisted that Iraq was his motherland and he did not need permission to go home.
He said neither the Iranian government nor the United States was putting pressure on Mr Hakim to delay his departure.
The Iraqi Shi'ites are concerned that the United States might try to deny them a role in a post-Saddam Hussein Iraq because of their ties with Tehran.
Their suspicion grew even further last week with the sudden appearance of a London-based opposition Shi'ite cleric in the Iraqi holy city of Najaf - apparently with the help of the American forces.
A spokesman for the London arm of the Supreme Council for the Islamic Revolution in Iraq (Sciri), Hamid al-Bayati, has denied that Washington is promoting a so-called moderate pro-American current among Iraqi Shi'ites at the expense of his group.
But he told the BBC that any Shi'ite cleric who cooperates with foreign forces would be regarded as a traitor.