US President Joe Biden and Iraqi Prime Minister Mustafa al-Kadhimi sealed an agreement on Monday formally ending the US combat mission in Iraq by the end of 2021, but US forces will still operate there in an advisory role.

The agreement comes at a politically delicate time for the Iraqi government and could be a boost for Baghdad. Kadhimi has faced increasing pressure from Iran-aligned parties and paramilitary groups who oppose the US military role in the country.

Biden and Kadhimi met in the...