Washington (CNN) Administration officials pushed back against lawmakers who are seeking to end US support for the Saudi Arabian-led coalition in Yemen unless its takes "urgent steps" to reduce the enormous toll of human suffering there.

Saudi Arabia, along with other Sunni Arab states, have had US backing since intervening in Yemen's civil war in 2015 to support the country's president and counter-rebels backed by Shiite Iran.

The conflict has left an estimated 10,000 civilians dead, 75% of the population in need of aid, and 8 million on the brink of starvation as cholera ravages Yemen's cities. In the vacuum created by conflict, groups such as al Qaeda in the Arabian Peninsula and ISIS have found space to thrive.

While lawmakers argued that the Saudi campaign is fueling suffering that will drive terrorism, administration officials said that countering Iran is essential and that the situation would be worse if the US pulls out -- though they had little evidence to show their efforts with the Saudis have lessened effects on civilians.

"The longer the civil war continues, the worse the humanitarian crisis will grow, and the more Yemen will serve as a staging ground for terrorist activities that threaten the US and our partners," said Sen. Todd Young, an Indiana Republican, during a Senate Foreign Relations hearing on administration policy on Yemen.

"Our values and our national security interests demand that we take additional action to improve the horrible humanitarian conditions in Yemen and end the civil war," Young said.

The Indiana senator is part of a bipartisan group proposing legislation that would require the State Department to repeatedly certify that Saudi Arabia is taking urgent steps to end the Yemeni conflict, ease the humanitarian crisis and lower the risk to civilians.

If State isn't able to do this using unclassified information, the bill would bar US air refueling for Saudi coalition aircraft focused on missions over Yemen. Saudi Arabia has conducted an average of 15 airstrikes a day for three years now, Democratic Sen. Chris Murphy of Connecticut estimated.

At the UN, where the Security Council gathered to meet on Yemen, US Ambassador Nikki Haley stressed that while the US wants peace, it has no intention of rewarding Iran and the Houthi rebels that Tehran backs.

"Iran and the Houthis, in particular, need a much better understanding of our seriousness when it comes to their destabilizing activity," Haley said.

She also stressed Saudi Arabia was entitled to defend itself from missile attacks by the Iran-backed Houthi rebels, particularly since they caused a civilian death.

"If a missile killed civilians in Washington DC, I know how we would respond," Haley said.

In Washington, the emphasis was on Yemeni civilians.

"The Senate has yet to take decisive action to influence the Saudi-led military operations and protect innocent civilians in Yemen," said Sen. Jeanne Shaheen, a New Hampshire Democrat who helped write the bill. "It's long past time to send a strong message to Saudi leadership that we have high expectations for our allies, particularly those who are benefiting from US military support."

US officials from the Defense and State Departments argued that the presence of US personnel helps to mitigate the toll on civilians.

"Curtailing US military support would not persuade the Saudi-led coalition to abandon its air campaign," said acting Assistant Secretary for Near Eastern Affairs, David Satterfield. If Washington backs away, Satterfield argued, Saudis could pursue defense relationships with countries that "do not have an interest in ending the humanitarian crisis, minimizing civilian casualties, or making progress towards a political solution.

The US has "fewer than 50 US military personnel" working in Saudi Arabia with the coalition, said Robert Karem, the Pentagon's assistant secretary for policy, "advising and assisting with the defense of Saudi territory, sharing intelligence, and providing logistical support," including aerial refueling.

Karem said that the US is "focused on helping the coalition avoid civilian casualties in Yemen." But when pressed by Maryland Democratic Sen. Ben Cardin, Karem said the US doesn't actually track the results of Saudi military activities.

"We see a difference in how the Saudis operate," Karem said before admitting that, "we do not have perfect understanding because we are not using all of our assets to monitor their aircraft."

"If we don't track the results of the Kingdom's military actions, how can we know civilian deaths are being reduced," Cardin asked. "You don't have direct information about it. This is the US reputation on (the) line. . . don't make statements you can't back up."

As that debate played out in the Senate Foreign Relations Committee, the UN Security Council gathered in New York to discuss the conflict, which the Special Envoy to Yemen called "this great tragedy."

Critics say the Saudi-led air campaign and particularly its closures of Yemen's ports have fueled famine, disease and the breakdown of the country's basic services. One of the world's poorest nations before the conflict began, Yemen now has nearly 18 million people struggling to find enough to eat, and 1 million cases of cholera -- a disease partly driven by the fact that 16 million people do not have clean water to drink.

Martin Griffiths, the UN Special Envoy for Yemen, told the council he plans to present them a framework for negotiations within the next two months.

Satterfield and Karem told lawmakers that Saudi Arabia is committed to political negotiations, but Murphy dismissed that claim as "spin."

"This impression that you're giving the committee that the Iranians don't want to come to the table and the Saudis and the Emirates do, is spin," he said. "The Saudis have made it pretty clear to everyone that's asked them that they are not going to come to the table until the military battle lines on the ground inside Yemen change."

He noted that for three years, Saudis have been trying to score military victories without success. "So why are the Saudis going to come to the table today?" he asked.

"The definition of insanity is doing the same thing over and over again and expecting (a) different set of results," Murphy said. "And I feel like that's where we are, [three] years into a conflict in which nothing has changed except for the worse."