In 2014 Russia-backed separatists used a blend of digital and traditional fighting during their takeover of Crimea, and the Pentagon took note.

As the Russians blitzed the contested eastern region of Ukraine with cyberattacks, electromagnetic jamming and unmanned aerial systems, the U.S. military closely monitored the battle tactics, according to officials speaking Oct. 8 at the Association of the U.S. Army’s annual meeting.

What Pentagon officials observed sparked change.

The events in Ukraine helped the U.S. military become more “threat informed in how we develop our future capabilities,” Maj. Gen. Garrett Yee told reporters while speaking about electronic and cyber warfare.

How the Russians embraced hybrid warfare showed just how effective overlapping these tactics could be.

Ukrainian forces have received Russian-backed text messages to "undermine unit cohesion and troop morale,” Col. Liam Collins wrote for the AUSA website. The Russian military has also targeted areas where a large number of cellphones have been detected with artillery strikes, Collins explained.

“In one coordinated action, electronic warfare is combined with cyberwarfare, information operations and artillery strikes to produce psychological and kinetic effects,” Collins wrote.

Experts and military officials say that the Russian tactics informed American cyber needs.

“When the Pentagon studied Russian aggression in the Crimea, a lot of it had to do with cyberattacks,” said James Montgomery, who handles cyber business development for Lockheed Martin, one of the prime defense contractors for the U.S. government.

In response, the Pentagon highlighted the need for increased “defensive cyber” from military contractors.

“The hardest part about defensive cyber is maintenance, and really it is keeping things together,” Montgomery said. The network “is a raging river that at any one point can branch off.”

The Pentagon has also asked defense contractors for stronger information and electronic warfare systems after the events in Ukraine, Montgomery told Fifth Domain.

In the past five years the Pentagon has invested in stronger cybersecurity due to the demands of hybrid warfare, according to experts and military officials.

The Army is doubling the size of its electronic warfare force and nearly doubling the training those troops receive before they are deployed, Brig. Gen. Jennifer Buckner said during an event at AUSA. She added that the Army is integrating electronic warfare units into more parts of the military.

But despite the call to action caused by the Russian aggression, the U.S. military has not fully transformed into a hybrid fighting force, Aaron Brantly, a cyber policy fellow at the Army Cyber Institute told Fifth Domain.

It was an “ongoing process” for the U.S. military to adapt to the type of hybrid warfare presented in the Ukraine, Brantly said. “You are taking an enormously large bureaucracy and trying to get them to work together. This isn’t a thing that happens overnight.”