President Joe Biden is ending US military support for the war by its Saudi allies in Yemen, the White House said on Thursday ahead of the Democrat's first major foreign policy speech.

"He's going to announce an end to American support for offensive operations in Yemen," National Security Adviser Jake Sullivan told reporters shortly before Biden was to make the speech at the State Department.

"That's a promise he made in the campaign he will be following through on."

The end on US military support for the Saudi-led coalition fighting in Yemen reverses former president Donald Trump's policy of providing logistical assistance and selling huge amounts of advanced weaponry such as precision-guided bombs.

Signalling Washington's new approach to the war, which has led to a humanitarian crisis, the Biden administration is also appointing a Yemen envoy, Timothy Lenderking, said a person familiar with the matter.

Biden "will talk about the United States playing a more active and engaged role in the diplomacy to bring an end to the conflict", Sullivan said.

 Germany troop changes frozen 

Biden will also freeze plans set in motion by Trump to reduce the US troop presence in Germany, which has been a cornerstone of NATO security since the start of the Cold War.

"Today [Biden] will announce... a global force posture review and during the pendency of that review will freeze any troop redeployments from Germany," Sullivan said.

Trump's decision was seen as linked to his tense relationship with Germany and the European Union over trade issues, but sparked concerns that he was weakening the West's security in the face of a resurgent Russia.

Biden has quickly toughened Washington's posture towards Moscow.

He is blaming the Kremlin for a massive cyber attack and US presidential election meddling, and also calling out Russia over the jailing of Alexei Navalny, one of the few remaining opponents of President Vladimir Putin.

"Unlike the previous administration, we will be taking steps to hold Russia accountable for the range of malign activities that it has undertaken," Sullivan said.

"We will do that at a time and a manner of our choosing," he said.

On Myanmar, Biden is considering new sanctions that would target specific individuals and entities connected to the all-powerful military, which took over the country after detaining civilian leaders this week.

"We are also looking at specific targeted sanctions both on individuals and on entities controlled by the military that enrich the military," Sullivan said.

Rebuilding alliances 

In excerpts of the speech released by the White House, Biden will call for renewed alliance-building and US leadership on the world stage.

"We must meet this new moment of accelerating global challenges - from a pandemic to the climate crisis to nuclear proliferation - challenges that will only be solved by nations working together in common cause," Biden was to say.

"Over the past two weeks, I've spoken with the leaders of many of our closest friends - Canada, Mexico, the UK, Germany, France, NATO, Japan, South Korea, and Australia - to begin re-forming the habits of cooperation and rebuilding the muscles of democratic alliances that have atrophied from four years of neglect and abuse," Biden was to say.

"America's alliances are among our greatest assets. And leading with diplomacy means standing shoulder to shoulder with our allies and key partners once more."