U.S. Sends More Aid To Ukraine Amid Tensions With Russia

President Zelensky of Ukraine has requested more financial and military aid from President Biden. The US plans to evacuate its embassy in Ukraine, while two planeloads of military assistance have arrived in Kiev. The US and NATO are prepared for both diplomatic and military responses to a potential Russian invasion, which could happen soon due to the buildup of Russian troops. President Biden has warned American citizens in Ukraine to leave, emphasizing the seriousness of the situation.

What actions has President Biden taken to warn American citizens in Ukraine?

What scenarios did President Biden mention regarding the involvement of American troops?