The head of the UN education, science and culture agency on Monday called on president-elect Joe Biden to re-commit the US to international institutions, notably Unesco.
"Global challenges of today call for a renewed commitment from the #UnitedStates for common goods #Science #Education #Culture," Unesco Director-General Audrey Azoulay said in a tweet.
The US withdrew from the Paris-based agency at the end of 2018, accusing Unesco of anti-Israel bias.
Instead, it established an "observer mission" to replace its representation at the agency.
The United States had already suspended membership payments in 2011, angered when Unesco members granted Palestine full membership of the body, despite opposition from its ally Israel.
Washington opposes any move by UN bodies to recognise the Palestinians as a state, believing that this must await a negotiated Middle East peace deal.
A source at the organisation said that since Biden's election victory "we're getting positive signals at Unesco".