Donald Trump’s long-awaited Muslim ban became a reality today. No, you might say, it’s not actually the proposal he outlined during the campaign. True, the ban doesn’t cover every Muslim globally, just a set of Muslims from countries Trump perceives, rather arbitrarily, to be dangerous.

But today’s announcement is anchored in his campaign rhetoric, and the fact that every country on today’s list is a Muslim-majority nation confirms that he meant what he said – that Muslims are dangerous and need to be treated differently than any other set of people.

This is why today’s proposal is likely to get Americans killed.

ISIS, the most dangerous of a global array of radical Islamic terrorist groups, is in retreat. Every day, they lose more territory, and it is only a matter of time before their self-proclaimed caliphate disappears before the world’s eyes. The continual loss of territory robs from ISIS one of their two main rationales for existence – the creation of a geographic entity based on their perverted interpretation of Islam.

But ISIS has a second purpose – to take part in an imagined global struggle of civilizations between Christians and Muslims. President Obama and President Bush before him knew the danger of stoking talk of war between east and west. Obama knew how important this kind of talk was to ISIS’s recruitment and expansion, and he went out of his way to tamp it down.

The decision to turn our backs on millions of men, women, and children attempting to flee torture and terror shrinks us as a nation, and marks an unconscionable abandonment of our founding principles.

Trump has now handed ISIS a path to rebirth. They can and will use his announcement today as confirmation that America is at war with Muslims, especially those Muslims living in desperate circumstances. Their recruitment bulletin boards will light up with new material. Their entreaties to would-be lone wolf attackers in America will have new energy and purpose.

All the work we have done to cut down on extremist recruitment at home and abroad now goes out the window. It’s a new day for terrorist recruiters.

And the list is dangerous for other reasons. It makes Americans think that terrorists can be contained simply by focusing on a few countries that are often in the news. But the real threats to America are much broader than just these countries. Where is Saudi Arabia on this list? Or Pakistan? Does Trump not recall that the attackers on September 11th came not from Syria or Iran or Sudan, but from Saudi Arabia, our supposed ally? And what about Europe, a continent that now enjoys relatively unfettered travel rights to the United States? Radicalized European citizens have already carried out massive terrorist attacks, and under current law, they can travel to the U.S. without almost any security screening. Terrorist threats do not originate in one set of countries, and thus a geographic approach is feckless.

If President Trump was serious about tackling the terrorist threat, he would make sure the Europeans were sharing counterterrorism intelligence with each other, and with us, so we can track potential terrorists no matter what country they come from. Another commonsense measure would be to ban people on the terrorist watch list from buying deadly firearms in America. But rather than do any of these things that would actually make Americans safer, Trump is pursuing misguided policies rooted in bigotry and fear.

And the boon to flailing terrorist groups is just the beginning of the tragedy of today’s announcement. During my last trip to the Middle East, I was upbraided by our allies in the region for our country’s refusal to help them with the flow of refugees out of Iraq and Syria. Over and over they told me, as they had told the Obama administration, that we would never be perceived a partner in the fight against Islamic extremism if we washed our hands of the refugee problem.

We assail Libya and Yemen and Syria and Iraq with bombs, and then simply expect other countries to deal with the consequences. We make the mess, then expect others to clean up. This infuriates our friends and damages our partnerships. Now, Trump’s Muslim ban will risk severing ties between us and many of these nations. They will see our policy as xenophobic and detrimental to the displaced persons crisis in the region. Our ability to build a truly multi-national response to extremism will become impossible.

We assail Libya and Yemen and Syria and Iraq with bombs, and then simply expect other countries to deal with the consequences.

Finally, the decision to turn our backs on millions of men, women, and children attempting to flee torture and terror shrinks us as a nation, and marks an unconscionable abandonment of our founding principles. Remember, those who make it into the U.S. refugee program have survived the worst of the worst – they are those who are so badly injured, so in danger, that they cannot survive in refugee camps. The vast majority of them are women, young children and the elderly. They are desperate and scared, and without harbor in the United States, many of them will perish.

We are a nation founded by religious refugees. Over and over, we have opened our doors to those fleeing war and terror. Jews in the wake of the Second World War. The Vietnamese in the 1960s and 1970s. Bosnians and Albanians during the Balkan War. I am proud to represent Connecticut, a state which is a testament to this past practice. Each time we found ways to sort out the good guys (99%) from the bad guys (1 percent). There were terrorists in Vietnam and the Balkans who wanted in – we kept them out. We can do the same here. We can protect ourselves from terror and rescue others from terror – these are not mutually exclusive ends.

And we must do both. Trump’s Muslim ban is a moral abomination. It is fundamentally un-American. And it is dangerous – it will give life back to the terrorist movement and eventually get Americans killed.

We knew today was coming. Trump means what he says, and now his offensive ramblings against people of Muslim faith are edified in law. But we don’t have to accept it. We must fight this new policy. We must seek to rescind it. We must let the world know that Trump’s discriminatory views do not reflect the true America. And we must rally Americans who think that keeping Muslims out keeps us safe to understand that this policy does exactly the opposite.

This isn’t who we are. It’s not who we should be. And I will fight this policy with all that I have.