The general nominated to be the first US "war tsar" has said he had initial doubts about the US troop surge in Iraq but that it should be given time.
Lt Gen Douglas Lute was nominated by President George W Bush
Lt Gen Douglas Lute, picked last month by President Bush to oversee the wars in Iraq and Afghanistan, was speaking at his Senate confirmation hearing.
He said he had warned that pouring more troops into Iraq would only work if the Iraqi authorities also made efforts.
The Senate committee is expected to confirm Gen Lute in the post.
Once confirmed, he will report directly to President George W Bush as deputy national security adviser.
Gen Lute, 55, was appointed after a lengthy search in which several candidates apparently turned down the position. He is currently serving as director of operations at the Pentagon.
Speaking at his Senate hearing, Gen Lute acknowledged that media reports that he had had misgivings about the surge policy favoured by the White House were true.
"I expressed concerns in the policy development stage... that this not simply be a one-dimensional surge," he said.
LT GEN DOUGLAS LUTE
Graduated from West Point academy 1975
Active in 1991 Gulf War
Commander, Kosovo, 2002
US Central Command, 2004-06
He had warned the strategy would "likely have only temporary and localised effects" unless it was accompanied by efforts by the Iraqi authorities and US non-military agencies.
He told the committee that it was still "early days", however.
"Early results are mixed. Conditions on the ground are deeply complex and likely to continue to evolve, meaning that we will constantly have to adapt."
He said the Iraqi government had taken some steps to support the strategy but described Iraqi progress on security as "uneven so far".
Senator Carl Levin, Democratic chairman of the Senate Armed Services Committee, said Gen Lute was in an "unenviable position" and questioned how much of an impact his posting would have.
"How much more time should we give after four years in Iraq?" Mr Levin asked.
"Baghdad is burning while the Iraqi politicians avoid accepting responsibility for their country's future."
Once confirmed, Gen Lute would begin work against the backdrop of attempts by congressional Democrats to restrict funding for Iraq, or to tie future funding to evidence of progress.
It is expected he would speak for the president concerning developments in the conflict areas and co-ordinate efforts in the state and defence departments.
Several White House security officials have left the administration in recent months.