The Pentagon's new "National Military Strategy" released Wednesday warns that the threat of major war with another nation is "growing" and significant changes to the military personnel policies and culture will be required to succeed in the 21st century.

The 17-page document was updated to reflect a new global security situation in which the U.S. is facing near-peer adversaries like Russia and China while simultaneously trying to diffuse non-state militant groups like the Islamic State.

"Since the last National Military Strategy was published in 2011, global disorder has significantly increased while some of our comparative military advantage has begun to erode," Army Gen. Martin Dempsey, chairman of the Joint Chiefs, wrote in his introduction to the strategy document.

"We now face multiple, simultaneous security challenges from traditional state actors and transregional networks of sub-state groups — all taking advantage of rapid technological change," Dempsey wrote. "We are more likely to face prolonged campaigns than conflicts that are resolved quickly."

The strategy also outlined significant shifts that the Pentagon expects to see inside the U.S. military,

"To enhance our warfighting capability, we must attract, develop, and retain the right people at every echelon. Central to this effort is understanding how society is changing," according to the strategy document.

The previous version of the strategy made scant mention of personnel matters. But the new version alludes to how a new generation of young people, who are often more technologically savvy and socially liberal, will force change upon military culture.

"Today's youth grow up in a thoroughly connected environment. They are comfortable using technology and interactive social structures to solve problems. These young men and women are tomorrow's leaders and we need their service. Therefore, the U.S. military must be willing to embrace social and cultural change to better identify, cultivate, and reward such talent," according to the document.

That will include "exploring how our personnel policies and promotion practices must evolve to leverage 21st-century skills," the document noted, a reference to the Pentagon's growing push to reform the way the military manages its people.

"Also critical to building the best military possible are our efforts to further integrate women across the force by providing them greater opportunities for service," the document said.

In assessing the growing risks that the U.S. faces around the world, the document focuses on the importance of partnerships to maintain the delicate security balance around the globe, something Pentagon officials have been pushing over the last several months.

Speaking after the release of the document, Dempsey said the strategy acknowledges that American success "will increasingly depend on how well our military instrument supports the other instruments of national power, and how it enables our network of allies and partners.

The strategy specifically calls out Iran, Russia and North Korea as aggressive threats to global peace. It also mentions China, but notably begins that paragraph by saying the Obama administration wants to "support China's rise and encourage it to become a partner for greater international security," continuing to thread the line between China the economic ally and China the regional competitor.

"None of these nations are believed to be seeking direct military conflict with the United States or our allies," the strategy states. "Nonetheless, they each pose serious security concerns which the international community is working to collectively address by way of common policies, shared messages, and coordinated action."

Later, the document notes that "today, the probability of U.S. involvement in interstate war with a major power is assessed to be low but growing."

However, "hybrid conflicts" — not just the Islamic State, but forces such as the Russian-backed rebels in Ukraine — are likely to expand.

The strategy also hits on the concerns highlighted by Defense Secretary Ash Carter and his deputy, Bob Work, over the last six months that the U.S. no longer is guaranteed technological superiority, or that in conflicts with groups like the Islamic State, that technological superiority may not be a guarantee of victory.

Defense News staff writer Aaron Mehta contributed to this report