10/07/2015 21:55 EDT | Updated 10/07/2016 01:12 EDT

Hillary Clinton's email server was hit by repeated cyberattack attempts from foreign countries

WASHINGTON — A document obtained by The Associated Press shows that Hillary Rodham Clinton's private email server was the subject of attempted cyberattacks originating in China, South Korea and Germany after she left office in early 2013.

A letter from Sen. Ron Johnson, the Wisconsin Republican whose Homeland Security and Government Affairs Committee is investigating Clinton's email arrangement, says the attempts were apparently blocked by a "threat monitoring" product that Clinton's employees connected to her network in October 2013. But there was a period of more than three months from June to October 2013 when that protection had not been installed.

It was not immediately clear whether the attempted intrusions into Clinton's server were serious espionage threats or nuisance attacks.

Ken Dilanian, Jack Gillum And Stephen Braun, The Associated Press