President Biden informed Congress on Thursday that he has terminated the national emergency over the U.S.-Mexico border that former President Trump first declared in a Feb. 2019.

Why it matters: Trump used the national emergency proclamation to divert billions of dollars in Pentagon funds toward building a border wall, after it became clear that Congress was opposed to additional funding. The declaration prompted dozens of lawsuits and attempts by Congress to block Trump from fulfilling one his main 2016 campaign promises.

What they're saying: "I have determined that the declaration of a national emergency at our southern border was unwarranted. I have also announced that it shall be the policy of my Administration that no more American taxpayer dollars be diverted to construct a border wall, and that I am directing a careful review of all resources appropriated or redirected to that end," Biden wrote in a letter to congressional leaders.

Go deeper ... Biden's Day 1 challenges: The immigration reset