The points of friction were that in hurricane Katrina, federal forces came in to the disaster response under the command of the President without sufficient dialogue with the governors about which specific disaster response operations were most important for that governor. There needs always to be civilian leadership over defence operations, and in our system governors—not the President of the United States, but governors—have primary responsibility for the public safety of their citizens.
On May 6th, 2014. See this statement in context.