When I met with Syrian refugees in Jordan and Turkey a few months ago, many were already struggling with the realization that they would not be able to return home any time soon. For some, home no longer even existed. "If we returned to Syria, we have nothing left," a father of two told me. "The house, the store, the car, they were all destroyed. There is nothing left there."

As the crisis enters its fourth year, the scale of suffering in Syria is tremendous; so, too, is its impact on the region. More than 6.5 million people have been displaced within Syria and more than 2.6 million have fled the country in search of refuge. The UN Refugee Agency expects this number to rise to more than 4 million by the end of this year. More than 587,000 Syrian refugees have fled to Jordan, more than 649,000 have fled to Turkey, and nearly 1 million have fled to Lebanon, where Syrian refugees now constitute a quarter of the fragile country’s population.

In his testimony before the US Senate Foreign Relations Committee last week, Jan Egeland, Secretary General of the Norwegian Refugee Council and former United Nations Undersecretary-General for Humanitarian Affairs, noted:

If we do not act now to protect the region’s future, the fallout from this conflict will be felt for generations.

This is already apparent. Despite their generosity, Syria's neighbouring states are struggling to provide basic needs to refugees, some of whom are living in squalor. And the sheer scale of the humanitarian crisis also threatens the stability of the region, including that of key US allies like Jordan.

And yet, so far, the American response has been wanting. With more than $1.7bn in aid so far, it is the single largest donor to the Syria humanitarian response, but the United States resettled a mere 36 Syrian refugees in 2013. As of February 2014, the US has resettled only 25 more. That's a total of 121 since 2011, out of over 2 million refugees.

If the country with the largest resettlement program in the world doesn't step up, who will?

This January, US officials indicated that the government expects to accept referrals for several thousand Syrian refugees in 2014. But so far, the United States has not announced a commitment to resettling a significant number. Why?

Part of the challenge is that sweeping provisions in US immigration law have so far allowed refugees to be mislabeled as supporters of terrorism for innocent contacts with armed groups – such as the sale of a falafel sandwich – even though the refugees are vulnerable, have engaged in no wrongdoing and pose no threat to the United States. This February, the Obama administration took a step in the right direction by allowing case by case adjudication – with extensive background checks, safeguards and exceptions – of some cases that might have otherwise been blocked from consideration.

The US isn't the only state reluctant to welcome some of Syria's refugees. The UK, for example, announced plans to resettle the modest number of 500 Syrian refugees, but only after public criticism by film stars Colin Firth and Emma Thompson. Other European countries, including Bulgaria and Greece, have even imposed obstacles preventing Syrian refugees from crossing into their countries. Such responses set a poor example for the frontline states, which must keep their borders open to refugees as a requirement of international law and to prevent an even greater humanitarian catastrophe.

It's clear what is needed: while the international community must devise a comprehensive long-term plan for addressing the refugee crisis, a crucial part of that plan must include sharing the responsibility of hosting refugees.

And the United States should lead this effort. As the world's richest country, and one that justifiably prides itself on protecting refugees, it needs to be doing much more. This year, the US should aim to resettle at least 15,000 Syrian refugees, and should continue to significantly increase the number it takes in. The credibility of the US and its ability to effectively press other states to increase their own efforts depends on it.

It shouldn't stop there. The US should continue to fund relief and development, prioritizing refugees living outside camps and the infrastructure challenges of host communities. The US should also increase pressure on all parties to the conflict to permit humanitarian access inside Syria, and should make make clear that those who obstruct access will be held accountable.

When I was in Jordan, a 20-year old mother who had fled from Syria to Amman implored: "Please don't let people in America forget about us," she said. We shouldn't.