A ransomware attack on software vendor Kaseya may have compromised hundreds of companies and raises new questions about relations between the United States and Russia.

Security experts blame REvil, a cybercrime organization linked to the Russian government, for the July 2 attack on Kaseya’s VSA network monitoring and management software. Thousands of small and medium-sized businesses use the software package, and up to 1,500 businesses were affected by the attack, the company said on July 5. The company has been issuing frequent updates in its efforts to contain the attack.