US President Joe Biden declared "America is back" in an address to the nation Thursday afternoon.

"Diplomacy is back at the center" of US foreign policy, the president said as he announced a slew of policy changes from the previous administration.

"We're going rebuild our alliances. We're going reengage the world and take on the enormous challenges we face dealing with the pandemic, dealing with global warming and again standing up for democracy and human rights around the world," Biden said.

One of the changes Biden announced was the end of US support for all offensive operations in Yemen, ending American backing for the Saudi-led conflict against the Iranian-backed Houthi rebels in the war-torn nation.

The president called the conflict "a war that has created humanitarian and strategic catastrophe," but pledged to "continue help and support to Saudi Arabia."

He also pledged "freeze any troop redeployments from Germany" during a "global force posture review" led by Defense Secretary Lloyd Austin, "so our military footprint is appropriately aligned with our foreign policy and national security priorities."

In addition, Biden pledged to raise the cap on the number of refugees admitted into the US each year.