Columnist

Various cultures have different phrases for expressing the idea of having it both ways at once. "To take a swim and not get wet" is an Albanian proverb. Poles talk about "having the cookie and eating it." Iranians want "both God and the sugar dates."

The Trump administration has been weighing a contemporary geopolitical version of this straddle. Hard-liners have been urging the president to decertify the Iran nuclear agreement but insist that he wants to strengthen the deal, not break it. The idea is enticing politically, certainly, but it has as much chance of working as (forgive me) "washing your fur but not getting wet," as a German aphorism puts it.

Sen. Tom Cotton (R-Ark.), a leading critic of the Iran deal, described this ambiguous diplomatic approach this week at the Council on Foreign Relations. "I don't propose leaving the deal yet. I propose taking the steps necessary to obtain leverage to get a better deal." Cotton wants decertification, but no sanctions, so that the United States can . . . what? Apparently, the idea is that U.S. pressure will convince Iran to make unilateral concessions that it refused during the 13 years the deal was being negotiated.

Magical thinking is always appealing in foreign policy, but it usually produces nothing more than fairy dust. In this case, there is no evidence that putting the agreement in limbo will bring any security benefits for the United States or Israel. It will introduce uncertainty where the United States and its allies should most demand clarity — in insisting on compliance by all sides with an agreement that caps Iran's centrifuges and stockpiles of enriched material for at least another decade.

Defense Secretary Jim Mattis, hardly a dove on Iran, bluntly told the Senate Armed Services Committee on Tuesday that the nuclear deal was "something that the president should consider staying with." When pressed by Sen. Angus King (I-Maine) on whether he thought the pact was in the United States' national-security interest, Mattis paused and answered: "Yes, Senator, I do."

Officials speak truth to power at their own risk in President Trump's Washington. So Mattis's argument for sustaining what the president has called "one of the dumbest [and] most dangerous" deals was important, though the outcome of the debate still isn't clear. It's probably because of Mattis's military advice, however, that Trump has dropped his campaign talk of simply tearing up the agreement.

How would Iran react? Seyed Hossein Mousavian, a former Iranian official who stays in close touch with his ex- ­colleagues, told me recently that if Trump doesn't certify, but Congress doesn't re-impose sanctions, and the other P5+1 negotiators assure full implementation, then Iran may continue to adhere to the agreement. But he cautioned that this line is opposed by some political factions in Iran that argue for suspending the pact if Trump challenges Iranian compliance.

As for the administration's hope of forcing Iran to renegotiate the "sunset" provisions and other details of the agreement, Mousavian says that's a nonstarter in Tehran.

The real challenge with Iran isn't the nuclear issue, which was put in a box for at least a decade by the agreement, but Tehran's aggressive behavior in the region. Iran and its proxies continue to destabilize the Middle East. They seek to manipulate and control nearly every major capital: Beirut, Damascus, Baghdad, Saana. According to the White House, Iranian proxies are mining the Bab el-Mandeb Strait, pointing missiles from Yemen toward Riyadh and Abu Dhabi, and seeking to carve a zone of influence on the ruins of the Islamic State in Syria and Iraq.

The administration claims to be focused on this big Iran problem. Would that it were so. Officials say that Trump has signed off on a broad strategy that makes Iran's behavior the central issue going forward. But the decertification debate will probably dominate the headlines over the next weeks and months — needlessly focusing attention on the one part of the Iran problem that is capped and manageable, and defusing efforts on the real challenge.

There's a final, crucial reason Trump should certify that Iran is complying with the nuclear deal: because it's true. Even Cotton conceded as much this week, arguing against certification "not primarily on the grounds related to Iran's technical compliance, but rather based on the long catalogue of the regime's crimes and perfidy against the United States."

A question for the Iran hawks: If the United States refuses to certify an agreement when a country is "technically" in compliance, why would any other country ever make a deal with us again? A great country keeps its word.

Read more from David Ignatius's archive, follow him on Twitter or subscribe to his updates on Facebook.