A television screen in Seoul shows President Trump and North Korean leader Kim Jong Un. (Ahn Young-Joon/AP)

Bob Menendez represents New Jersey in the U.S. Senate, where he is the ranking Democrat on the Foreign Relations Committee.

Under President Trump’s watch, North Korea has steadily built a significant weapons arsenal in violation of international law. It has also successfully tested three intercontinental ballistic missiles and its largest nuclear weapon yet. Only after affirming his country’s nuclear status has Kim Jong Un struck a conciliatory tone.

The improving relations between North and South Korea present a historic opportunity for denuclearization and lasting peace. And I applaud the return of American citizens held captive by North Korea.

But we must be clear-eyed about the challenges ahead. The president’s impulsive and erratic approach to foreign policy has left our allies confused and our adversaries emboldened. If he wants to take advantage of this critical opportunity, he needs something that he has repeatedly been incapable of providing: disciplined leadership and a real strategy.

Already the summit is on shaky ground after North Korea threatened to cancel it over routine joint military exercises with South Korea. Trump must see past this gamesmanship and effectively turn Congress’s maximum economic pressure policy into the diplomatic leverage needed to come to a workable agreement. North Korea’s nuclear and missile programs remain a threat to the United States, and we need diplomacy rooted in shrewd pragmatism about Kim and his regime.

In hastily agreeing to a summit without any preconditions, Trump has already handed Kim an enormous victory by legitimizing a brutal regime that violates the human rights of its own citizens and advances aggressive policies abroad. We are barreling toward a meeting that, under the best of circumstances, will be a high-wire act with no safety net. We will face off with the dictator of a pariah state whose regime has a long history of breaking promises and violating agreements.

Yet rather than empower the State Department and the skilled diplomats best equipped for this major diplomatic initiative, the administration has eviscerated it. To this day, Trump has failed to even nominate an ambassador to South Korea.

Before this summit takes place, it is critical to consider three traps we need to avoid so that this meeting does not turn to disaster.

First and foremost, we cannot make any agreement that we cannot effectively monitor or verify. Trump might not realize it, but every president since 1994 has received a “denuclearization” commitment from North Korea. The history of these negotiations is littered with broken promises to halt or disable Pyongyang’s nuclear and missile programs.

That’s why before the United States agrees to any concessions, North Korea must provide complete transparency of its nuclear weapons program and ongoing verification by international inspectors. The administration must keep its eyes on the prize, and the president must exercise discipline when presented with whatever shiny objects, photo-ops or public displays of flattery that Kim will use to distract us from obtaining key information, such as the location of North Korea’s fissile material, warheads and ballistic missiles.

Second, we must avoid making further concessions that would damage U.S. partnerships in the region, as our entire Asia-Pacific strategy is built upon our dynamic alliances with Japan, South Korea, Australia and others. These alliances remain critical for maintaining peace, stability and economic prosperity throughout the region. Any agreement that ends our alliances and presence in the region would be a historic mistake that jeopardizes U.S. interests.

Finally, the administration must resist the temptation to discard diplomacy altogether if the summit fails to produce an immediate comprehensive denuclearization agreement. Time and again, this administration has oscillated from one policy extreme to another. If a summit is not wholly successful — or frankly, even if it is — Trump cannot yank us back to a war path with North Korea.

Days before becoming national security adviser, John Bolton saw the summit as a useful opportunity — not to resolve the nuclear crisis peacefully, but to act as a steppingstone to military action. Much as he sought any justification for the 2003 invasion of Iraq, Bolton’s grim theory was to demand Pyongyang’s immediate surrender of its nuclear weapons to the United States. Kim’s refusal, he argued, would expose him as unserious about denuclearization, leaving unilateral military action as the only option.

Although we of course all want Trump to succeed in reaching an immediate and complete denuclearization deal, even a partial agreement that verifiably begins the process of rolling back North Korea’s nuclear and missile programs would constitute success. Such an agreement should be combined with continued pressure, a strong deterrence posture and a continuation of the emerging North-South dialogue. This would over time provide a reliable pathway to full denuclearization.

To reaffirm our commitment to a diplomatic solution, I plan to introduce legislation that provides stringent congressional oversight of our diplomacy with North Korea and any agreement that emerges. It would also help this administration avoid the traps that Kim might seek to set.

While Pyongyang’s track record leaves considerable room for skepticism about its intentions, Congress must embrace its role in shaping U.S. foreign policy and do everything possible to ensure that the Trump administration pursues a diplomatic strategy that serves American interests and averts catastrophic military confrontation.