I feel the finger on the trigger. I also feel it on the button.

“Dear President Obama,” the letter begins. It goes on to remind him of something he said in his 2008 presidential campaign: “Keeping nuclear weapons ready to launch on a moment’s notice is a dangerous relic of the Cold War. Such policies increase the risk of catastrophic accidents or miscalculation.”

The letter, from the Union of Concerned Scientists, is signed by 90 scientists, including 20 Nobel laureates. It continues: “After your election, you called for taking ‘our nuclear weapons off hair-trigger alert.’”

Presidential campaigns, mass killings, war . . . nuclear war. Washington, we have a problem.

The time has come for extraordinary change. Who we are — this monstrous, planet-destroying entity called America — needs to be decommissioned and reconstructed on a foundation more solid than the present myths of greatness, greed and entitlement. We need a new vision, a manifestation of the moral intelligence that is also part of who we are: a vision of how this nuclear-armed, gun-saturated nation can disarm itself and, in the process, become a force for real peace.

“We urge you,” the scientists write, “to take U.S. land-based missiles off hair-trigger alert and to remove from U.S. war plans the option of launching these weapons on warning. The United States should encourage Russia to follow suit, but it should not wait to act. Taking these steps would have profound security benefits for all Americans by reducing the risk of nuclear disaster.”

I think about this in the context of the Orlando murders and see a gruesome similarity between U.S. militarism and the violent forays of armed loners — and the “concentrated horror” both inflict. The main difference, as far as I can tell, is that the human carnage and environmental destruction resulting from U.S. militarism remain emotionally invisible, you might say, to the American public.

In a powerful essay at TomDispatch, William J. Astore, a retired U.S. Air Force lieutenant colonel, takes a harsh look at the wars we have waged from on high since World War II, noting that “for all its promise of devastating power delivered against enemies with remarkable precision and quick victories at low cost (at least to Americans), air power has failed to deliver, not just in the ongoing war on terror but for decades before it. If anything, by providing an illusion of results, it has helped keep the United States in unwinnable wars, while inflicting a heavy toll on innocent victims on our distant battlefields.”

He adds: “At the same time, the cult-like infatuation of American leaders, from the president on down, with the supposed ability of the U.S. military to deliver such results remains remarkably unchallenged in Washington.”

He points out that in the Korean War, in the early ’50s, the U.S. pounded North Korea with 635,000 tons of bombs and 32,557 tons of napalm. Cities were leveled, but the war ended in no better than a stalemate; more than half a century later, Korea remains a bitterly divided nation.

Then came a decade of war in Southeast Asia. By the time this pointless war ended in dishonorable defeat, the U.S. had dropped, according to Astore, “a staggering seven million tons of bombs, the equivalent in explosive yield to more than 450 Hiroshimas,” on Vietnam, Laos and Cambodia. We also poisoned the jungle with defoliants, having given ourselves free rein to commit environmental carnage with horrific consequences well into the unforeseeable future for absurdly limited tactical ends.

It took a decade and a half for the military-industrialists to overcome “Vietnam syndrome,” the public’s weariness of war, but eventually they were able to put Iraq in the crosshairs, devastating the country with bombs and missiles — including munitions made of depleted uranium — over the course of several decades, spreading immediate carnage and long-lasting genetic damage, all of course to no end except endless war.

And the War on Terror, which I call the War To Promote Terror, is still going on 15 years later, with no end in sight. The funding for it is unquestioned and seemingly limitless. The point of it is also unquestioned, except at the social and political margins. It certainly is unquestioned in the 2016 presidential race, especially the winnowed down version of it — Trump vs. Clinton — that’s left. The military-corporate branch of the American government remains well beyond public reach.

And so I think about the Orlando murders and the unending grief they have caused in the context of all the murders the U.S. and its allies and its enemies have committed in the name of war.

And I think about the congressional failure to enact any legislation in regard to the sale of assault weapons in the context of the letter 90 scientists associated with the Union of Concerned Scientists wrote to President Obama, reminding him that before he was president he expressed awareness of the danger of having nuclear weapons on hair-trigger alert, and asking him to remove the 450 land-based nuclear missiles (but not the submarine-based missiles) from high alert.

And I wonder at my certainty that the request will be ignored. And I wonder what will happen next.