File it under “things you don’t see very often.” A press release from Republican Ed Royce, chairman of the House Foreign Affairs Committee, declaring, “I appreciate the efforts of Secretary Kerry….”

Accolades from across the aisle have been few and far between for an administration that has suffered an almost endless string of foreign-policy reversals since 2008. Indeed, Secretary of State John Kerry had been the front runner on many pundits’ short lists of “most likely to be the first official to be ousted from the second-term team.”

Yet Kerry appears to have averted a catastrophic crisis in Afghanistan—one that might have brought down the whole American project. There is much that Kerry could learn from this triumph about what realistic diplomacy looks like.

Part of the plan for getting the United States out of Afghanistan once and for all, without turning the country back over to the Taliban, called for creating a stable, durable political process. The blossoming of democracy, however, seemed to be imploding last month, when a run-off election between presidential candidates Abdullah Abdullah and Ashraf Ghani became mired in widespread election fraud. Both candidates suggested they might form their own government. If that happened, the country might just fall apart.

Last week, Kerry jetted in to talk both sides back from the brink. News circulated that if the two presidential candidates went their separate ways, Obama might well pull the plug on all U.S. support. It’s no secret that influential voices in the White House have long advocated the “zero option,” so the threat certainly seemed credible.

But, Kerry did the deal. He brokered an agreement from both candidates that they would hold off. Instead, they will stand down while all the votes in the election are audited.

Crisis averted—for now.

From the outset of his presidency, Obama has long trumpeted the practice of substituting “soft” power for hard options. That predisposition is a core tenet of the Obama Doctrine. But for all its efforts, the White House has never had much to show. Putin revoked the Russian “reset.” The administration hasn’t come close to closing any major trade deals. Secretary Kerry’s optimism that he could broker peace between Hamas and Israel has been shattered by sharply escalated violence.

The president’s deal on Syria’s chemical weapons has failed to slow the spiraling death count in that country. Indeed, violence there has now spilled over and overwhelmed Iraq. And while the president’s focus may have shifted to Asia, none of our major Asian allies seem much reassured. The major concerns in the region—from the resurgence of transnational terrorism, to the instability of North Korea, to China’s burgeoning and increasingly bellicose territorial claims—have not lessened. And few believe the White House can close a credible nuclear deal with Iran and P+5 before the July 20 deadline.

Kerry’s success in Kabul stands in sharp contrast to rest of the Obama foreign-policy muddle. Diplomacy worked on this occasion largely because it was the rare occasion when the White House allowed for the proper use of the instrument.

The very first rule of good diplomacy is that it must be realistic—that what the diplomats are asked to accomplish is suitable, feasible and acceptable. This administration has too often tried to use diplomacy to solve every problem—rather than only the problems statecraft can solve.

Diplomacy’s second law is that soft and hard power work best hand in hand. Henry Kissinger once declared, “Power without legitimacy tempts tests of strength; legitimacy without power tempts empty posturing.” That’s dictum Obama seems not to have heard. Instead, the White House tends to preface all diplomatic initiatives with acts of deliberate self-weakening, leaving itself negotiating from a position of weakness.

In Kabul, Kerry avoided both the pitfalls of poor diplomacy. A deal was certainly doable. Both Abdullah Abdullah and Ashraf Ghani are Western educated. They want to keep the United States and other allies engaged in the country. The last thing either man wants is to be left standing alone, between the warlords and the Taliban.

Furthermore, they still need the United States. The Afghan military is performing better and more consistently than expected. Compared to the Iraqi military, they look like the Army of the Potomac at Appomattox. But there is little chance that progress could be sustained without coalition support.

Yes, Washington’s influence over Kabul has declined since Obama announced the timeline for the drawdown and began to pull back U.S. troops. On the other hand, the United States still has enough presence and the Afghans have enough needs that our diplomats can play “let’s make a deal” with a straight face.

After all, neither presidential aspirant could really relish the thought of trying to set up their own government and think they would ever spend an easy night holding the presidential title.

The problem for President Obama is that virtually none of the other major foreign-policy conundrums he faces will yield as easily to a diplomatic sit-down as the crisis in Kabul. When it comes to dealing with Russia, China, North Korea, Iran and the mayhem in Syria and Iraq, Mr. Obama should accept that, for the foreseeable future, there are no good outcomes that can be readily won at the negotiating table.

There is, however, an important role for diplomacy in the sunset of the Obama presidency. The president and his secretary could profitably spend their waning days reassuring friends and allies that America will be a capable, responsive and consistent power.

Obama could start by showing real leadership at the NATO summit. He could then present a focused, proactive agenda at the upcoming U.S.-Africa Leadership Summit. He could press to reestablish the “quad” talks (India, China, Japan and the United States) in Asia. He could take an active interest in promoting a major free-trade agreement—the Trans-Pacific Partnership.

Unfortunately, right now none of those possibilities seem to be in the offing. Instead, Mr. Obama continues to send Mr. Kerry out like forlorn hope on what looks mostly like “show,” rather than “show me” diplomatic missions.

 - James Jay Carafano is vice president of defense and foreign policy studies for The Heritage Foundation.