(VOVworld)-Security for Donald Trump’s inauguration on Friday will be a major challenge. The US presidential inauguration is one of the most heavily guarded events in the world, but the openness of the event complicates those efforts. 

Nearly one million spectators are expected to attend the Inauguration Day ceremonies and 99 groups are expected to rally in favor of or against the new president. The main focus will be Friday's swearing in of the 45th president on the West Front of the Capitol Building in Washington D.C, followed by the inaugural parade from the Capitol to the White House. US Secretary of Homeland Security Jeh Johnson said officials know of no specific credible threat directed toward the inauguration but law enforcement is concerned with homegrown violent extremism, acts of lone wolves and people who have self-radicalized.

Workers building viewing stands at the Capitol for President-elect Donald Trump’s inauguration. (Source: Jonathan Ernst/Reuters)

Johnson said there will be some 28,000 officials dedicated to security for the inauguration, including the Secret Service, the Transportation Security Administration, and the Coast Guard, and some 7,800 National Guard troops. Clear plates of bulletproof glass will be used to protect VIPs and the rooftops will be patrolled by government snipers. The FBI will have radiation and chemical and biological detectors around the area. US security agencies plan to fortify perimeter locations around inauguration events with dump trucks, trucks carrying cement and buses. After terrorists drove trucks into crowds in Nice and Berlin last year, officials are protecting against a similar action in Washington. Noting that the airspace above Washington is already off-limits to drone flights, as well as most other air traffic, Johnson said unauthorized flights are “something we have planned for, and there is technology to deal with it”. Security is estimated to comprise half of the total expense of inauguration events, estimated at 200 million USD.