Army Gen. Mark A. Milley said people need to remember why NATO began in 1949.
The defensive alliance was put in place to prevent the outbreak of great power war, and that's still a valid task, the chairman said. "Sometimes, people can become complacent and assume that peace is the state of nature," he added. "Peace doesn't happen by accident: It happens because of effort, resources, commitment, allies banding together … to maintain a strong, cohesive alliance."
The chairman said it has been obvious for a long time that Russia wants to divide NATO and make it weaker, if not destroy it. "That would be to their advantage," he said. "It's to the disadvantage of Europe and the United States if NATO would just collapse and fall apart."
It's worth noting that there were two big periods of continental peace in Europe before NATO, Milley said. "One was following the Treaty of Westphalia [in 1648)] after the 30 Years War, where Europe tore itself apart," he said.
The great power peace following it lasted about 100 years. Great power wars returned with the Napoleonic wars that ended in 1815, Milley pointed out. The countries of Europe put in place a balance of power so no great power fought another great power, he explained. “That lasts 100 years until 1914, and it breaks down,” he said.
The world faced great power wars through World Wars I and II, slaughtering between 145 million and 155 million people around the world, the chairman said.
"NATO was put in place, and the structures of the international order were put in place, at the end of World War II to prevent a great power war," he said. "They weren't put in place to prevent terrorism. They weren't put in place to prevent Vietnam or Korea. They were put in place [to prevent] that great power war."
The chiefs of defense spoke with NATO Secretary General Jens Stoltenberg. Milley said the NATO leader spoke about the situation in the Middle East and his conversation with President Donald J. Trump about increasing NATO support to the training mission in Iraq. The chairman said he saw support from his counterparts for the alliance doing more in the Middle East.
The NATO Military Committee has to come up with capabilities that would be needed, the general said. "I think you've got to look at what capabilities nations can provide," he added. "So, one for example, kind of an obvious one, would be maybe some ballistic missile defense support, because there are NATO allied troops at these various camps that just took Iranian ballistic missiles. So that's a possibility."
He said he also can see providing logistics support, and possibly additional military training teams, to increase the volume and capacity of the Iraqi security forces. "Right now, the NATO mission in Iraq is somewhere around 500 guys," Milley said. "It's a noncombat train, advise, assist role ... building [Iraqi] capacity to secure themselves. The United States still thinks, and NATO still thinks, that's a valid mission and will continue that mission. We have no intention of not continuing that mission."
NATO is a force for peace, Milley said.
"This alliance is important," he said. "It's important to Europe, it's important in the United States and we should not become complacent about it. And things like defense spending and working together and interoperability and maintaining commitments to each other is important for preventing a great power war and in order to maintain peace and stability."