The commitment also came as a pleasant surprise, Gates told reporters Tuesday as he traveled to Kabul, Afghanistan, to meet with U.S. troops and Afghan leaders.
"Frankly, my hope was that we could get 5,000, so a commitment for (7,000) was better than I expected," Gates said. "And from what I am hearing ... the commitments may go higher than that."
Gates' unannounced visit to Afghanistan comes a week after President Barack Obama said an additional 30,000 U.S. troops would be deployed to Afghanistan.
"Since spring, I have been surprised by the change of tone on the part of our allies," Gates said on the Defense Department Web site. "There has been a ... realization of the importance of being successful in Afghanistan, of the consequences to the alliance of not being successful, and just a greater sense of commitment to this thing."
The Pentagon chief also reaffirmed continued U.S. support to Pakistan in its fight against terrorism on its side of the Pakistan-Afghanistan border, considered a safe haven for terrorists.