American pharmacies are still grappling with difficulties providing prescriptions Friday following a cyberattack against one of the nation's largest health-care technology companies that is now being blamed on a "suspected nation-state associated cyber security threat actor." 

Tricare, the military health care program, says on its website that "Military clinics and hospitals will provide outpatient prescriptions through a manual procedure" until the ongoing cyberattack against Change Healthcare "is resolved."  

Change Healthcare, a company handling orders and patient payments throughout the U.S., first noticed the "cyber security issue" affecting its networks Wednesday morning on the East Coast.  

The company is a division of UnitedHealth Group, which wrote in an SEC filing that it has "identified a suspected nation-state associated cyber security threat actor" that has "gained access to some of the Change Healthcare information technology systems." 

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The filing did not identify the alleged country involved. Fox Business has reached out to the White House for comment. 

On its website this morning, Change Healthcare said it is "experiencing a cyber security issue, and our experts are working to address the matter.  

"Once we became aware of the outside threat, in the interest of protecting our partners and patients, we took immediate action to disconnect our systems to prevent further impact," the company continued. "At this time, we believe the issue is specific to Change Healthcare and all other systems across UnitedHealth Group are operational." 

Pharmacies across the country put out notices Wednesday that the attack on Change Healthcare was disrupting their ability to process patients' orders. 

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"This is impacting all military pharmacies worldwide and some retail pharmacies nationally," Tricare said. 

"Military pharmacies will give priority to urgent prescriptions followed by routine prescriptions. Each military hospital and clinic will continue to offer pharmacy operations based on their local manning and resources," it added. "Please be patient while pharmacies take longer than usual to safely fill prescription needs." 

A spokesperson for pharmacy chain CVS told Fox Business on Wednesday that the company is aware of the outages but that there is "no indication that CVS Health's systems have been compromised." 

"We’re continuing to fill prescriptions, but in certain cases, we are not able to process insurance claims, which our business continuity plan is addressing to ensure patients continue to have access to their medications," the spokesperson added.

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A spokesperson for Walgreens said its pharmacy operations and the "vast majority" of its prescriptions were not impacted. 

Fox Business’ Timothy Nerozzi contributed to this report.