The United States says it may cut its number of troops in Afghanistan after elections there in September.
Myers expects Pakistan to continue anti-al-Qaeda operations
General Richard Myers, chairman of the US Joint Chiefs of Staff, made the comments during a visit to the Afghan capital, Kabul, on Friday.
The US has recently increased its force to step up the hunt for Osama Bin Laden and al-Qaeda fighters.
There are now about 15,500 US troops in Afghanistan and Gen Myers said he thought the nation was "pretty secure".
Gen Myers said: "We've ramped up our presence here a little bit, anticipating and trying to ensure that we have no more violence as we head towards elections.
"So we're a little stronger than we have been. That does ebb and flow. It's quite likely we could go back down to lower
The general, who had flown in from Iraq, said he expected Pakistan to continue operations against al-Qaeda and Taleban fighters along the border.
"My understanding is they [Pakistan] are going to remain committed to activities in the tribal areas and to try to help with this
problem," Gen Myers said.
The general held meetings with the commander of the US forces in Afghanistan, Lieutenant-General David Barno, and the US ambassador, Zalmay Khalilzad.
Gen Myers said: "I think generally most of the country is pretty secure as a matter of fact."
Elections in Afghanistan had to be postponed to September from June following violence in the north and south.
The UN has warned elections will fail unless security can be improved.