After miles of splendid scenery along the Kennebec River, when you turn onto the Sagadahoc Bridge toward Bath, the first glimpse across the river is of Bath Iron Works’ tall cranes. I confess to a certain ambivalence about that sight.

On one hand, BIW represents a great Maine shipbuilding tradition. Of all the big private yards that once populated the coastline, this one remains. It builds some of the largest, most sophisticated vessels in the world, and maintains standards for design, engineering and delivery that are a tribute to the thousands of shipbuilders who’ve passed through its gates.

On the other hand, for many years BIW has built ships only for the U.S. military. The USS Zumwalt, its current project, is a $3.5 billion stealth destroyer, one of only three to be built before BIW resumes construction of the previous destroyer class, usually described as a cost-saving decision.

The Zumwalt and its two companions to come fell victim to the Pentagon’s aim of building ships constantly more advanced than anything that came before. The electronics on the new ship are beyond anything a video game addict could imagine. Its power plant could light up a city.

But no other country is building anything remotely like the Zumwalt, nor does anyone appear likely to.

There was a time in the memory of those still living, before World War II, when the concept of a standing army was considered suspect and un-American. Every major war had been followed by an equally rapid demobilization. After World War I, there was no Army worthy of the name, and isolationism had never been stronger.

The Cold War and the contest with the Soviet Union changed all that, but the Cold War ended in 1991 with the formal breakup of the Soviet empire and its rapid demilitarization. There isn’t a military power anywhere to match the United States. The military alliances we retain in Asia makes it highly unlikely that China, as some have suggested, could become a significant threat to U.S. interests.

BIW produces warships that may never see combat, just as General Dynamics’ other major New England shipyard, Electric Boat in Groton, Conn., produces attack submarines without adversaries.

Is warfare on a world scale still something we should prepare for?

The United States now has the luxury of leading something we haven’t seen in 2,000 years, the pax Romana, a 150-year period when Rome so dominated Europe, west Asia, and the Mediterranean that warfare almost ceased. And the decline of Rome, historians say, had little to do with diminished military capacity, but with internal political divisions that sapped its economic strength.

It’s worth wondering whether American thinkers even grasp the nature of the opportunity to make peace, rather than war, the standard of international affairs.

Since the end of the Cold War, we’ve fought two large and mostly pointless wars in Afghanistan and Iraq. There have been a number of smaller military actions, some justified, some not.

But it is with the Obama administration that we see most clearly the choice. If John McCain had been elected in 2008, rather than Barack Obama, it’s quite possible we would have been at war with Russia in Georgia — the former Soviet republic, not the state. That’s what McCain’s statements implied.

If Mitt Romney had been elected in 2012, it’s equally plausible we would have opened a new front over the Benghazi attack in Libya, an event that — despite the best saber-rattling efforts — never was more than a skirmish.

Obama himself came close to war, in Syria, when he advocated a military response to poison gas attacks. But he pulled back, and the result — abandonment of chemical weapons and comprehensive United Nations inspections — could have prevented all the misery of the Iraq war, too, had George W. Bush been willing to wait a few months.

The historic agreement with Iran is the latest fruit of Obama’s preference for diplomacy over military threats.

Yes, it’s a tentative pact, but it’s also the first actual agreement with Iran since the hostage-taking at the American embassy in 1979. What’s historic is that it takes the Middle East a long step away from conflagration.

The success of American diplomacy undoubtedly has a great deal to do with maintenance of an overwhelming military advantage. But keeping that advantage could, in time, become less costly as it becomes possible to stand down in even the most hostile of current environments.

Will BIW ever build ships of commerce and pleasure instead of war? I wouldn’t pretend to know. But, heading west across the Kennebec, it would be an even more awesome sight.

DOUGLAS ROOKS is a former daily and weekly newspaper editor who has covered the State House for 29 years. He can be reached at [email protected].