There are drone jammers that block radio frequencies and GPS signals in a area making the used drone inoperable. (https://crab.wordpress.com/2010/02/11/how-to-d

There are drone jammers that block radio frequencies and GPS signals in a area making the used drone inoperable. (https://crab.wordpress.com/2010/02/11/how-to-down-a-drone/ https://crab.wordpress.com/2010/02/11/how-to-down-a-drone/) These devices are used at film sets and important buildings which makes it probable that they are a measure to protect the president.