Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

The head of the National Security Agency said Tuesday that the potential for Russia to harm the U.S. electoral process in the upcoming general election is a concern.

Cybersecurity officials have become increasingly worried about the issue in the wake of revelations that Russia-based hackers were behind two recent hacking attempts into state voter registration databases.

One incident included stealing information from roughly 200,000 Illinois voting records. In another attempt in Arizona, cyber criminals used malware to try and breach voting records, forcing state officials to disable online voting registration for nine days as they investigated the unsuccessful hacking.

At least one official told NBC News recently that Russian intelligence agencies were part of the hacking attempts. Several other officials told NBC News that they haven’t confirmed the Russian government’s involvement, but remain concerned.

Get breaking news and insider analysis on the rapidly changing world of media and technology right to your inbox. This site is protected by recaptcha

Related: Russians Hacked Two U.S. Voter Databases, Officials Say

During a Senate Armed Services Committee, Sen. John McCain, R-Ariz., asked about the possibility that Russia “could somehow harm the electoral process” in his state and “disrupt the voting results in the upcoming election.”

Admiral Mike Rogers, head of the NSA and U.S. Cyber Command, spoke about the disparate structure with some states voting manually and others electronically.

“But is it a concern?” McCain asked.

“Oh, yes sir,” Rogers responded.

Neither Rogers nor Marcel Lettre, the principal deputy under secretary for intelligence at the Defense Department, would provide any specifics about the recent online intrusions in Arizona, citing the ongoing investigation.

And neither would say whether the cyber targeting was from a foreign nation state or not.

The FBI and DHS have an “aggressive” investigation underway, Lettre said.

While the current voter registration-related hacks are not currently considered a national security threat, there has been some conversation about elevating cyber attacks against U.S. state and federal electoral facilities to that level, officials said.

Rogers also acknowledged that ISIS continues to plan attacks on the United States.

The terror group “is the most adaptive target I have ever worked in 35 years as an intelligence professional,” Rogers said.