Responding to Sen. Bernie Sanders’ (I-Vt.) call for the Trump administration take immediate action to address extreme poverty in the U.S. after a United Nations report found that tens of millions of Americans are suffering “massive levels of deprivation,” U.S. Ambassador to the U.N. Nikki Haley declared in a letter to Sanders on Thursday that it is “patently ridiculous” for the U.N. to even examine poverty in America because it is “the wealthiest and freest country in the world.”

Sanders was quick to issue a forceful response to Haley on Thursday, arguing that the U.N. should examine widespread poverty in the U.S. precisely because it is the wealthiest nation on the planet.

“You are certainly right in suggesting that poverty in many countries including the Democratic Republic of Congo and Burundi is far worse than it is in the United States,” Sanders wrote in a letter to Haley on Thursday. “But what is important to note about poverty in America is that it takes place in the richest county in the history of the world and at a time when wealth and income inequality is worse than at any time since the 1920s.”

The Vermont senator continued:

The scathing U.N. report that Haley denounced in her letter to Sanders as “misleading and politically motivated” found that more than 18 million Americans are living in “extreme poverty,” and that the Trump administration’s attacks on the remnants of America’s social safety net are going to make this crisis worse.

In his response letter to Haley on Thursday, Sanders concluded: “As it happens, I personally believe that it is totally appropriate for the U.N. Special Rapporteur to focus on poverty in the United States.”