Hillary Clinton goaded her Republican rival with a video Monday that mocked his push for more secretive military communications amid a spate of high-profile cybersecurity breaches.

At a rally in Colorado Springs, Colo., last week, Donald Trump argued the military could safeguard its planned operations by putting them on paper rather than digitizing them.

"Everybody's being hacked," Trump said on Friday. "Let's not send it over the wires so everybody's probably reading it."

"I like the old days, especially for the military and things like that," Trump said. "You want to attack or you want to do something, it's called [a] 'courier.'"

"It's called, 'Let's put it on a thing, put it in an envelope and let's hand it to the general,'" he added, pantomiming the act of writing words on a notepad.

Clinton's decision to joke that Trump should use "carrier pigeons" to transmit classified information raised eyebrows given her own struggle with the proper treatment of sensitive material.

FBI Director James Comey's announcement on July 5 that Clinton had demonstrated "extreme carelessness" in her transmission of classified emails as secretary of state underscored one of the biggest weaknesses of her candidacy: the voters' lack of trust in her ethics.

Her social media joke came amid an FBI investigation into hacks of the Democratic National Committee, the Democratic Congressional Campaign Committee and her own campaign.