See more of the story

For the first time since the end of the Cold War, the Pentagon has a genuinely new strategy: Focus on our rivals — Russia and, in particular, China — and maintain a competitive advantage over them. If we fail to do so, Defense Secretary Jim Mattis warns in his 2018 National Defense Strategy, we may lose the next big war against these nations. If that happens, say goodbye to the free and open international order the U.S. has built and upheld since the 1940s.

So will the Defense Department take the big steps needed to implement this strategy? That's the key question — and this is a key moment. That's because, earlier this year, Congress gave the Defense Department its largest budget increase since 2001 — a 10 percent raise, after inflation. In return, the Pentagon must show meaningful progress in realizing this strategy.

And it needs to do so in a hurry. China and Russia have spent decades building militaries specifically designed to fight and beat ours. Meanwhile, we have focused on rogue states and terrorism, taken a largely business-as-usual approach to modernization and robbed the Peter of advanced capabilities to pay the Paul of day-to-day force employment. This route, as the strategy makes clear, is a losing proposition.

We need modernization not just in general terms, but modernization and advanced capabilities designed to defeat Russia or China's theories of victory. They have spent years working to undermine our successful Desert Storm approach and have basically cracked the code. Now it is time for us to turn the tables — before we lose our edge.

That requires major change in what we buy, how the force fights and how we integrate with allies and partners. The operational concepts that worked against Iraq in 1991 must be left in the past. We need to move away from the large and vulnerable ships, the fixed bases and the short-range aircraft and munitions upon which we have long relied. We need to revamp our space, logistics and cyber architecture. And we need to rethink military plans that focus on establishing dominance in every domain before pushing the enemy back.

Such predictable and routinized operations might work against rogue nations, but they won't work against the militaries of China or Russia. Instead, we must concentrate on building and maintaining a force capable of taking on and besting a top-tier adversary under the assumption that U.S. forces will be contested at every step by highly capable opponents.

We must figure out how to blunt and reverse Chinese or Russian gains without the kind of dominance the U.S. could establish over Iraq or Serbia. We must move toward integrating artificial intelligence and unmanned systems capable of autonomous operations, in conjunction with manned platforms and on their own. We must introduce genuinely new capabilities into the force, not just incrementally modernized legacy systems. And we must develop novel ways of fighting and exercising.

Accomplishing this means either not doing some things or doing other things in a less expensive way. For instance, we cannot squander the readiness of our forces in the fight against terrorism, as we have too often done. But we need to be prepared to leave expensive platforms that don't fit the new priorities on the cutting-room floor, no matter their proud history or political constituencies.

Starting soon, Pentagon leaders will decide what their next budget submission will look like. As Deputy Defense Secretary Patrick Shanahan put it, this is their chance to create a "masterpiece." They have the strategy, the money, the vision and the bipartisan political support. Now is the chance to implement urgent change at significant scale — and show Congress, the American people, our allies and, perhaps most importantly, our potential foes that our armed forces are and will be ready to fight and defeat any comer.

If the Pentagon and Congress don't take this opportunity, we might not get an opportunity until a crisis has already arrived — which may be too late.

Robert O. Work served as deputy secretary of defense from 2014 to 2017. Elbridge Colby served as deputy assistant secretary of defense from 2017 to 2018. Work is a distinguished fellow and Colby the director of the defense program at the Center for a New American Security. They wrote this article for the Washington Post.