Once they were heard from, in the early 1990s, and their voices projected a clear sense of national unity and power.

Led by Republican President George H. W. Bush, the United States pulled off one of the great diplomatic coups in recent history — the peaceful reunification of Germany, with Moscow’s cooperation, and then crushed an Iraqi attempt to subjugate Kuwait by sending 500,000 troops to the Middle East. No one at the time questioned America’s fierce determination. By word and action, Bush and his senior advisers spoke the language of national pride and resolve.

Where are they now? Why their silence?

At another moment of international doubt and disruption, in which Russia plays a central role, and President Donald Trump plays a baffling role, we hear little to nothing from both Bush 41 and George W. Bush and their senior aides.

They are all Republicans.

Are they proud of their president, also a Republican? Or offended by him and his policy? If so, why not speak out? Why their silence?

These are all tough and experienced people, all actors on the world stage. None is a political novice. Bush 41 was surrounded by a very able cast of characters: James Baker as Secretary of State, Dick Cheney as Secretary of Defense, Brent Scowcroft as National Security Adviser, Colin Powell as Chair of the Joint Chiefs of Staff, Robert Gates as Deputy Director of the CIA, General Norman Schwartzkopf as commander of U.S. forces in the Mideast. World War II veteran Robert Dole led Republicans on Capitol Hill. Bush 43 could rely on Cheney as Vice-President, Powell as Secretary of State, Gates as Secretary of Defense, Condoleezza Rice as National Security Adviser and Secretary of State.

We hear an occasional whimper of disagreement with Trump’s policy toward Vladimir Putin’s Russia from Republican congressional leaders, all apparently fearful of upsetting the president’s vaunted “base.”

But where are the Bushes? Powell? Gates? Rice? Rumsfeld? Cheney? Scowcroft? They are not running for office. They are “appalled,” we’re told behind a cupped hand, by Trump’s mad Russia antics, and yet they remain silent, as if in a church of party purity.

Joe Scarborough of “Morning Joe” fame, once a Republican congressman from Florida, asks in amazement about the 71 percent of Republicans, who continue to support the president’s odd relationship with Russian President Vladimir Putin.

He concludes “the Republican Party […] no longer deserves to survive.”

Columnist Michael Gerson wonders whether the president is “wittingly advancing the interests of a hostile power” in managing America’s dealings with Russia.

He asks: What is our current policy?

In the past, a form of sensible internationalism has usually prevailed in GOP policy. In 1952, most Republicans rebelled against isolationism and elected Dwight D. Eisenhower. In 1980, Gerson continues, many Republicans rejected Henry Kissinger’s realpolitik and embraced Ronald Reagan’s vision of America as the “city on a hill,” the natural home of freedom and democracy.

And now?

Trump bewilders all Republicans; yet an overwhelming percent still supports him and his Russia policy, even if they do not really understand it. The desire of congressional Republicans to retain control of the House and Senate appears to be more important to them than the national interest. While a deplorable position, it is still politically understandable. They want to be re-elected, and they love the perks of power.

Other Republicans might enjoy the weirdness of a Trump presidency, seeing it as another episode of NBC’s “The Apprentice” show, and appreciating the fruits of continued economic growth.

But where are the voices of the traditional Republican foreign policy establishment?

Gates? Rice? Powell? The others?

Does their silence suggest that they are now more loyal to Trump and the GOP than to the national interests they so valiantly and successfully defended while in office?

Why do they remain silent?

They know better than many others that the nation is currently in desperate need of sensible guidance. More silence now only means more acquiescence to a faulty and dangerous policy.

If they were to break their silence now, they might encourage their timid congressional colleagues to speak up. Now is the time for honest talk.

If not now, when?

Kalb, senior adviser to the Pulitzer Center on Crisis Reporting and a senior fellow (non-resident) at Brookings, is author of the forthcoming book, “Enemy of the People.”