“The only existential threat to Israel is the marriage of extremist ideology set on the destruction of Israel and nuclear technology.” – Amos Yadlin, former Israeli Intelligence Chief

This week, we mark the 75th anniversary of Kristallnacht, the Night of Broken Glass. In a rampage of hate, 267 synagogues were destroyed, 7,500 Jewish businesses vandalized, 91 Jews murdered, and 30,000 Jews seized and forced to concentration camps. Kristallnacht was a message to the world that a war was being waged against the Jews.

Kristallnacht did not come from nowhere. Hitler’s intentions were clear long before 1938. Kristallnacht should have been a moment that the world stood up and confronted the Nazis. But the world hesitated, and it would be almost seven more years before the full horror of the Nazi killing machine was appreciated, and we first uttered the words, “Never Again.”

The world is watching again as the P5+1 sit down at the negotiating table in Geneva with Iran this week. Iran is seeking relief from the most stringent sanctions regime ever established. The sanctions are designed to persuade Iran to abandon its pursuit of nuclear weapons.

The sanctions exist in the context of repeated threats to wipe Israel off the map, and if we don’t act, Iran will soon have the means to do so. That is why the United States and its allies must demand Iran stop and reverse its nuclear weapons program—now and completely.

Stopping Iran requires continued sanctions pressure, not partial relief for partial steps. This summer, Iran installed more than 1,000 second-generation centrifuges at its underground, fortified uranium enrichment facility at Fordow. These machines are five times more efficient, dramatically reducing the time required for Iran to produce enough fissile material for a nuclear weapon.

And while Iran accelerates its uranium enrichment programs, it is also inching closer to completion of a plutonium reactor at Arak, providing a second pathway to a nuclear weapon capability. Once completed, this reactor, unlike Iran’s other reactors, cannot be attacked without a catastrophic radioactive release.

President Hassan Rouhani seems to present a more moderate face. But as we welcome the change in tone, he has yet to prove that his actions will match his rhetoric. We cannot forget that Mr. Rouhani comes to these negotiations because of the sanctions, not in spite of them. We must remember Mr. Rouhani is not the ultimate decision maker, that it is the Supreme Leader, Ayatollah Ali Khamenei. We must also remember that it was Mr. Rouhani who, just a decade ago, boasted of using negotiations with the world as subterfuge for Iran to secretly expand its nuclear program.

President Obama is right to talk with Iran to find a diplomatic solution. I share his objective of stopping Iran from acquiring nuclear weapons. But his request for the Senate to delay further action on sanctions will make it harder to achieve that goal. We simply do not have the luxury of time. To maximize the likelihood that negotiations will succeed, we must make clear to Iran that we will continue to increase the intensity and accelerate the pace of the sanctions until it gives up its quest for nuclear weapons.

That’s precisely the message we sent from the House of Representatives last July. I worked diligently to improve and help pass the Nuclear Iran Prevention Act (HR850). The House-passed bill includes two amendments I introduced to strengthen the sanctions effects. Despite its passage in the House with strong bipartisan support, the bill now sits in the Senate awaiting consideration. I call on Senator Reid to immediately bring it to the floor for a vote.

Last month, I co-authored a letter to President Obama stating, “until Iran fundamentally changes course, the United States must continue to toughen sanctions.” In total, 77 of my freshman colleagues joined me in signing the letter.

Yet while we work to increase the pressure, Iran continuously seeks to evade, circumvent, thwart and mitigate sanctions. It is therefore imperative that we continue to anticipate Iranian actions and prepare for even more sanctions pressure in the future.

Time is of the essence, and we must not allow Iran the opportunity to stall or delay. “Never Again” is now.