The Taliban has taken control of Afghanistan's second largest city, Kandahar. Now, the Biden admin. is sending 3,000 troops back into Afghanistan to help evacuate U.S. diplomats and civilians. Also, the FDA approves a third COVID-19 vaccine shot for those with weakened immune systems. And Homeland Security Secretary Alejandro Mayorkas says the U.S. is seeing an "unprecedented number of migrants" at the southern border with Mexico.