Russia’s aggression against Ukraine has led many Americans to re-evaluate President Obama’s mockery of those Republicans like Mitt Romney and Sarah Palin’s warnings about the geo-strategic threat that Vladimir Putin’s regime posed to the West. It turns out that the administration’s assumptions about not only Russia but also about the basic principles of U.S. foreign policy were mistaken. Not only did the magic of Barack Obama’s personality fail to tame Putin, Iran, Syria or North Korea. As our Abe Greenwald noted yesterday, the administration’s belief that America had transcended history and that the use of force was ineffective has again been thoroughly exploded.

But rather than prompt a far-reaching debate about the lessons to be drawn from this episode, many pundits, not all of whom are knee-jerk Obama defenders are calling for Americans to pipe down about whether the policies of the past five years are partly responsible for the mess in Eastern Europe as well as the fiasco in Syria, not to mention the ongoing administration attempt to forge a new détente with Iran. Instead, we are being told to be quiet and to let America speak with one voice, lest Putin or any other foe be encouraged by criticism of Obama. Not for the first time, Arthur Vandenberg’s famous 1947 quote in which he chided Republican critics of President Harry Truman’s foreign policy that “we must stop partisan politics at the water’s edge” is being disinterred in order to give the 44th president some respite from the beating he has been taking from conservatives about his policies. Though, as Robert Lieber wrote last month in the Washington Post, Democrats have ignored that principle in the last decade, Joe Scarborough, MSNBC’s token conservative is sounding that bipartisan theme both on “Morning Joe” and in a Politico op-ed. Scarborough argues that, “There is nothing more frightening to our enemies than a strong, unified American voice.” That’s true. But in the absence of leadership from the president and the administration, such a stance is impossible. Though loyalty to country must always trump partisanship, the effort to suppress a debate about foreign policy at a time when it is desperately needed is antithetical to the cause of creating that “strong, unified American voice.”

Scarborough is right that “political broadsides” are out of place “when the tanks are rolling.” But what’s happening in the Ukraine is not a replay of the Cold War confrontation with the Soviets about Berlin or the Cuban Missile Crisis, let alone a crisis when U.S. troops are on the move. The point about what is happening in the Ukraine is that both America’s friends and its foes take it for granted that the U.S. is out of the business of trying to defend freedom, whether in places where our military can make a difference or those, like in Ukraine, where we know it is not possible.

Given the hyper-partisan nature of our current political culture that is exacerbated by an equally divided media, it is hard to imagine the revival of the kind of bipartisanship that Vandenberg embodied under any circumstances. But in the absence of either strong leadership or an articulation of core American principles by the president it is impossible.

Were President Obama showing the kind of courage in standing up to Putin that other presidents of both political parties demonstrated in past disputes with the Russians, criticism of his foreign policy could and would be put off until later. But asking critics to be silent when no such effort to unify the country or to stand up for the interests of U.S. friends and allies is being put forward by the administration is itself mere partisan hogwash.

A debate about foreign policy is needed precisely because what we are witnessing is the product of a feckless foreign policy that primarily views geostrategic foes such as Russia and Iran as candidates for appeasement rather than dangerous enemies to be faced down with strength. For many liberals, Obama’s weakness is an asset to be applauded as they support his vision of a world in which American exceptionalism is mere chauvinism. However, this unilateral moral disarmament has severe consequences. Putin doesn’t need to listen to conservative criticisms of the president’s foreign policy to understand that Obama’s naïve conception of global politics to be encouraged to violate international law. He already came to that conclusion before he invaded the Ukraine.

Politics must now extend beyond the water’s edge not because conservatives wish to cripple administration efforts to defend American interests — as was so often the case in the past when the left treated anti-American forces as victims to be sympathized with rather than enemies to be despised — but because they want Obama to start behaving like someone who believes in his nation’s cause.

Far from undermining the president’s ability to deal with Putin or Iran, a debate about his policies is the starting point for a recovery of American strength. What Putin expects, indeed, what he is counting on, is the kind of apathy about Obama’s foreign policy that has allowed the president to evade accountability for stances that undermined allies and appeased foes for years. After years of being told, both by the left and some on the right that America can afford to retreat from the world stage, a vigorous discussion of foreign policy and the mistakes made by this administration isn’t a political luxury; it’s a necessity.