Update 2:40 p.m. ET: This story was updated after the meeting.
At the start of the event, Carter launched his pitch to allied nations: that history will remember those who assist in the fight against the Islamic State group, and those who don't.
"We will all look back after victory and remember who participated in the fight," Carter told an assembly of the anti-ISIS coalition gathered at NATO headquarters in Brussels, a not-so-subtle message to those who may be on the fence about contributing.
Carter said that "reinvigorating" the air campaign means "something very specifically in this case, which is air assets that have not been operating [as] part of our [theater of operations] and the air campaign, and were not doing so months ago, begun to do so in the last few weeks. It's a number of strike aircraft that's an important contribution."
He also acknowledged comments by Saudi officials that showed a willingness to deploy ground forces in Syria, saying the coalition discussed "training of both military forces and police forces," as well as "logistics support, sustainment, rebuilding of a kind that is going to have to go on Ramadi."
Speaking after the event, a senior defense official said Carter would have a Friday morning meeting with representatives of the United Arab Emirates.
Asked if Carter hoped to walk out of that meeting with another Sunni commitment, the official simply responded with "stay tuned."
"NATO as a new member would bring unique capabilities that could be brought to bear against ISIL, including experience in building partner capacity, training ground forces and providing stabilization support."
The nature of those commitments vary, and is not restrained to kinetic strikes.
In comments over the last week, Pentagon officials have emphasized that US will be asking for countries to contribute in ways beyond military assistance, such as training of police or providing funding for the Iraqi government.
However, it appears no new financial offers were made this week, with the senior official saying that several countries reminded the assembled of their "substantial" previous donations.
Carter, meantime, noted that countries will have several options in the near-term to make new contributions, whether materiel or not.
"In the coming weeks, there will be several opportunities to discuss and evaluate how well we are implementing our renewed commitments, including when your Chiefs of Defense meet in a couple of weeks, and when CENTCOM convenes the Coalition Force Generation Conference next month," Carter told the assembled nations in his opening comments, a point he reiterated after the meeting.
"He thinks there are additional contributions that could be made," the official said of Carter. "He feels good countries answered the challenge he put out there."
Aaron Mehta was deputy editor and senior Pentagon correspondent for Defense News, covering policy, strategy and acquisition at the highest levels of the Defense Department and its international partners.