The acting Pentagon chief said on Monday the FBI is assisting the US military in vetting more than 25,000 National Guard troops being deployed to assist in protecting the US Capitol around president-elect Joe Biden's inauguration for potential security concerns.

After the Jan 6 Capitol assault by supporters of President Donald Trump that resulted in five deaths and sent lawmakers into hiding, the US government has imposed unprecedented security surrounding the Capitol, including non-scalable fences rimmed with razor wire and a large security zone that the public is barred from...