By The Editorial BoardThe editorial board is a group of opinion journalists whose views are informed by expertise, research, debate and certain longstanding values. It is separate from the newsroom.

As recently as a decade ago, it would not have been hard to unite a broad majority of Republicans and Democrats around a shared idea of what America's military power should be for.

Defense of the homeland. Deterrence of would-be aggressors. Cooperation with treaty allies and protection of kindred democracies confronting common foes. Humanitarian aid and relief. The security of the global commons: sea lanes, air corridors, undersea cables, digital networks. Upholding the laws of war.

In sum, the ability to prevent war wherever possible and win it whenever necessary — all for the sake of a safer, more open, rules-based world.

The Trump administration brings a starkly different mind-set to the issue. Out with the Department of Defense; back to the Department of War. Well-established rules of engagement have yielded to blowing up small boats on the high seas. In place of standing with Ukraine’s embattled democracy against Russia’s invasion, the administration has adopted a course of moral equivalence between the two sides while seeking profits from the war through arms sales and mineral deals.

As for the kind of military alliance-building that typified American foreign policy for much of the 20th century, President Trump has reverted to threats of conquest more common in the 19th. And this is to say nothing of his efforts to deploy troops to American cities, impose political loyalty tests on senior officers or hamstring reporters at the Pentagon.

The Trump administration’s deployment of the National Guard to U.S. cities has drawn legal blowback from state and local leaders and harsh criticism from Democratic lawmakers.

Mr. Trump justifies his approach by claiming that the Pentagon needs an entirely different mentality for a new era of great-power rivalry. That’s not wrong. China’s rise and Russia’s revanchism means our security is more threatened today than it has been in decades. But so does the fact the United States has forfeited our military’s edge.

The president has done better than his predecessors in getting NATO allies to start budgeting adequately for their defense. He’s been right, also, to cut through layers of entrenched Pentagon bureaucracy that have prevented the military from keeping pace with technological changes that leave us increasingly vulnerable.

© The New York Times