AQABA, Jordan — Defense Secretary Jim Mattis on Sunday met with leaders from more than 40 nations in Aqaba, Jordan, to discuss the threat from terrorist groups and to hear how the United States military could help partner militaries prevent the spread of terrorism.

“Lessons learned can be shared, but at the same time, you have to size it up for its individual local conditions,” he told reporters after the meeting. “With our approach to our military relations, we work by, with, and through others and, in this case, it is by, with, and through African-led solutions to the instability of terrorism.”

The discussions took place at the annual Aqaba Conference where the focus was on West Africa and terrorist groups Boko Haram, the Islamic State in West Africa, and al-Qaeda. The conference was hosted by the King of Jordan Abdullah II bin Al-Hussein and Nigerian President Muhammadu Buhari.

Mattis noted the recent terrorist attack on Saturday by Boko Haram in Nigeria in which three young girls were used to carry out a suicide attack as aid workers were handing out food to those affected by their armed insurgency.

“Yesterday we had killed innocent people, murdered and wounded in Nigeria, for example, by Boko Haram — a reminder why we get together, why we share intelligence, and why we work by, with, and through the African nations and their organizations unique in this area,” he told reporters after the conference.

He also said ISIS is trying to seek safe haven in Libya as its physical caliphate is crumbling in Iraq and Syria. This year, the U.S. helped dislodge ISIS from gaining a foothold in Sirte, Libya, with airstrikes.

“You saw us push them on their back foot in January. We’ve done it again a couple of months ago. We’re doing it as we speak now,” he said.

But, he said, helping other nations prevent the spread of terrorism would not necessarily require U.S. troops or military action. He said sometimes it would require defense expertise by civilians, intelligence personnel, police forces, or aid workers.

“For example, if you need institutional reform, and if the military itself is not organized right, that breeds a certain requirement, certain types of people to come in. It may be more of my [Office of Secretary of Defense] policy people coming in, rather than uniform-wearing soldiers,” he said.

“If it’s something to do with, they’ve got a good military, it obeys civilian leadership, but it has not got the right skill-set, because the enemy is very adaptive, they learn how they can hide among innocent people, then we may bring in people to show how to do intelligence like that. That may actually involve more police forces coming in to do it,” he said.

And, he said, U.S. diplomats are “clearly” in the lead of efforts in the region.

As far as the U.S. military footprint in West Africa, Mattis said it would depend on the individual location and specific circumstances and be part of a whole-of-government approach.

He said he did not anticipate large numbers of U.S. forces or a reliance on young troops.

“I don’t think it will be large numbers at any point. That’s the whole point — we do it by, with, and through others — but they’ll probably be oftentimes more mature NCOs and officers, ones who’ve got a fair amount of experience. They won’t be young troops so much,” he said.

“At times you’ll see it be tactical trainers, where we teach tactics, marksmanship, first aid, what I’d call the basics of military forces, but it would — it would be shifted to whatever the specific problem is,” he said.

Breitbart News and other news outlets traveling with Mattis visited a training facility in Jordan on Sunday, where U.S. Marines were training Jordanian forces on marksmanship as one example of helping partner forces face terrorist threats. Southern Jordan sits right across from the Sinai, where ISIS conducted a terrorist attack last month.

The U.S. currently has a little over 6,000 forces all across Africa, in about 53 different countries, Chairman of the Joint Chiefs of Staff Gen. Joseph Dunford said last month. In early October, four U.S. soldiers were killed in Niger after being ambushed by terrorists during a reconnaissance mission.

But Mattis said U.S. troops are not the only ones providing military support to West African partner militaries — French, German, and British troops are also on the ground.

“Again, it’s not just by, with, and through the one nation we’re going in to help; it’s what other nations are there,” he said. “So, it’s all tailored to the specific conditions.”