Instead, Adm. Mike Mullen told a Kansas State University audience, success in the long wars will be determined by use of military and diplomatic powers, along with support from U.S. allies.
Mullen said there won't be a day when commanders "stand up and say 'That's it, it's over. We won."'
"We will win, but we will do so only over time and only after near-constant reassessment and readjustment," Mullen said. "Quite frankly, it will feel a lot less like a knockout punch and a lot more like recovering from a long illness."
Mullen said the outcome of Sunday's elections in Iraq will indicate how well the United States is doing there. He said in recent visits to Basra and Anbar Province that Iraqis were more concerned about economics and politics than security issues leading up to the vote, which he called "a good sign."
He said the U.S. intends to abide by its security agreement with Iraq and reduce the level of troops there by half to about 50,000 by August.
"There's every indication that an awful lot of Iraqis are going to vote," Mullen said. "I think what is next is dependent on the new Iraqi government."
Mullen, speaking as part of Kansas State's Landon Lecture series, said the use of military power should never be the last option, but potentially the best first option when paired with other means of national and international power.
He also noted ongoing operations in Afghanistan, where U.S. and Afghan forces have been embroiled in an offensive near Marjah to reclaim the area from Taliban fighters.
Mullen said commanders were taking a deliberate approach to minimize civilian casualties in an area considered the hub of Taliban activity, rather than using carpet bombing or missile strikes.
"Frankly, the battlefield isn't a field anymore," Mullen said. "It's in the minds of the people. It's what they believe to be true that matters."
He said there was no "American way" to fighting wars and that history shows the nation's enemies will adapt to U.S. strategy. Mullen said the U.S. will reassess its Afghanistan strategy in December and adapt accordingly.
"Trying everything else is not weakness," he said. "It means we don't give up. It means we never stop learning."
Mullen's lecture struck a tone similar to that of Defense Secretary Robert Gates when he was on the same Kansas State stage in November 2007. Both men said the United States must do more to encourage the use of "soft power" to resolve conflicts.