President Joe Biden has picked Julianne Smith to serve as undersecretary of state for political affairs, one of the highest positions in the State Department.
Ms Smith will fill the void left by Victoria Nuland, a State Department veteran who retired in March.
A native of Michigan, Ms Smith is currently the US representative to Nato, a position she has held since 2021.
In that role, she has helped the US through the Russian invasion of Ukraine as well as Nato's response to it.
Her predecessor, Ms Nuland, was also a strong supporter of Ukraine and was also a Nato ambassador.
Before her Nato role, Ms Smith was a senior adviser to the Secretary of State.
She served in the Barack Obama administration as the director of European and Nato policy at the Department of Defence, and then as deputy national security adviser to Mr Biden when he was vice president.
Her nomination has been sent to the Senate for approval.
The process could be complicated by some Republican senators who have threatened to block Mr Biden’s nomination requests after the conviction of former president Donald Trump in New York on 34 felony charges.
