Two Russian FSB agents and two hackers have been arrested as a result of a November-December 2014 hacking operation directed against users of Yahoo's email service that was said to affect "at least" 500 million people, as reported by NBC Chicago. The FSB officers are Igor Anatolyevich Sushchin, and Dmitry Aleksandrovich Dokuchaev. The hackers are Karim Baratov, and Alexsey Alexseyevich Belan, said to be among the Federal Bureau of Investigation's "cyber most wanted."

Belan and Baratov were reportedly paid by the FSB agents to hack into Yahoo Email Accounts and gain information described as having "intelligence value" to the Russian spy agency.

On Tuesday, Karim Baratov was reported to have been arrested in Canada. Retired Navy admiral James Stavridis, who served as the NATO Supreme Allied Commander Europe, called the situation "explosive," and stated that it "demands a response."

Thought be first U.S. criminal case 'brought against Russian government officials'

NBC reports that the Justice Department has previously pursued criminal cases against hackers from Russia, but that this is thought to be the "first criminal case brought against Russian government officials." FBI Special Agent John Bennett called the charges "unprecedented." Acting Assistant Attorney General for the Justice Department's National Security Division Mary McCord described the Yahoo hack as the largest "data breach" in the nation's history.

Detailing the actions of the Russian hackers, McCord added that information gained from the Yahoo hack allowed the operatives to access email accounts with other providers. The attack was said to affect both U.S. and Russian officials, including "cyber security, diplomatic, and military personnel," as well as Russian members of the press, employees of technology companies, and employees of "financial services, and other commercial entities." Examples of information stolen from user accounts include "gift card and credit card numbers," and 30,000 user contacts then put to use facilitating "an email scam."

$4.8 billion Verizon acquisition pushed back over 'data breaches'

In January, MarketWarch reported on Yahoo!

Inc.'s (Nasdaq: YHOO) planned $4.8 billion takeover by Verizon Communications, Inc. (NYSE: VZ) that would have to be pushed back from the first to the second quarter of 2017, with concerns over the hack being cited. YHOO shares were largely unchanged on the news Wednesday, trading down $0.09 to $46.28 on lighter-than-average volume. YHOO stock has outperfomed the Dow Jones Industrial Average over the past six months.