(Bloomberg) -- The Biden administration’s new United Nations ambassador vowed to re-energize diplomatic efforts to help bring an end to the world’s worst humanitarian disasters, citing crises in Yemen and Ethiopia.

Linda Thomas-Greenfield, who on Monday took over the UN Security Council presidency for March, said the goal will be to “bring awareness to the world about these growing and devastating humanitarian crises, and to call for leadership on the council for urgent, necessary solutions.”

“In these regions, war and instability have left millions of people and two million children under the age of five at risk of starvation and acute malnutrition,” Thomas-Greenfield, who’s in her first full week on the job as U.S. envoy, told reporters. “We cannot stand idly by.”

A military coalition led by Saudi Arabia has been waging a bombing campaign against Houthi rebels for six years in an effort to restore Yemen’s internationally recognized government. The war has created the world’s worst humanitarian crisis, with almost 50,000 Yemenis already starving to death in famine-like conditions.

Thomas-Greenfield’s decision to focus on Yemen in her debut at the Security Council comes as an appeal to raise money to fund the UN’s humanitarian response fell short of expectations, bringing in $1.7 billion. Secretary-General Antonio Guterres called the total pledge disappointing, noting that it was less than what was received in the previous two years.

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“Millions of Yemeni children, women and men desperately need aid to live,” he said. “Cutting aid is a death sentence. The best that can be said about today is that it represents a down payment.”

Earlier on Monday, U.S. Secretary of State Antony Blinken committed $191 million to the Yemen aid pledge. State Department spokesman Ned Price told reporters more funds may follow.

President Joe Biden announced last month an end to U.S. support for Saudi Arabia’s offensive operations in Yemen while tapping Tim Lenderking, a former deputy assistant secretary of State, to lead the U.S. diplomatic effort to end the war in Yemen.

Thomas-Greenfield, a career diplomat with experience across four continents and a former assistant secretary of state for African affairs, was approved by the Senate last week by a vote of 78-20.

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