President Joe Biden has formally approved additional US military deployments to eastern Europe, and the Pentagon is expected to announce Wednesday morning that the troops will deploy "in the coming days," US officials told CNN.

The deployments are a show of support to NATO allies feeling threatened by Russia’s military moves near Ukraine, the officials said.

The Pentagon is expected to announce that thousands of additional US troops will deploy to forward locations in Europe. The deployments will include roughly 2,000 US troops to Poland and an additional few thousand to southeastern NATO countries, including Romania, the sources said.

The US has put 8,500 troops in the US on heightened alert in case a NATO Response Force is called up and US forces are needed quickly. But the US and NATO have tens of thousands of other troops already in Europe to draw on for any additional deployments to Eastern European allies; some of the troops that will be deployed soon are already stationed in Europe, the sources said, while others will come from those in the US that are already on heightened alert.

The troops will operate on a bilateral basis with their host countries, since NATO has not yet activated a multinational response force. CNN reported last week that the US and a handful of allies had been in discussions to deploy thousands more troops to Eastern European NATO countries before any potential Russian invasion of Ukraine as a show of support in the face of Moscow’s ongoing aggression.

Biden also said last Friday that he would be moving the forces “in the near term,” as Russia has continued to build up forces near Ukraine, sparking fears of a renewed invasion even as diplomatic efforts to de-escalate tensions have continued.