BBC NEWS | World | Middle East | Rumsfeld warning to Iraq leaders
Mr Rumsfeld urged the new Prime Minister, Ibrahim Jaafari, and the new President, Jalal Talabani, to avoid delays in setting up the new administration.
"It's important that the new government be attentive to the competence of the people in the ministries and that they avoid unnecessary turbulence," Mr Rumsfeld told journalists on his pre-dawn flight into Baghdad.
He said it was important for the security forces to continue building their strength because US forces were not going to be there for ever.
The defence secretary also praised progress made in forming a leadership that spanned Iraq's diverse groups.
Mr Jaafari acknowledged there would be problems ahead but expressed optimism that the new government could meet those challenges.