Senate investigators say Chinese opioid manufacturers have been exploiting a screening weakness in the U.S. Postal Service in order to sell and ship large amounts of illicit drugs like fentanyl to dealers in the U.S., according to the results of an investigation published Wednesday. Chinese officials responded Thursday, noting that it “stands ready” to coordinate with U.S. authorities to help curb the illegal drug flow. “The Postal Service will continue to work tirelessly to address this serious societal issue,” said spokesman David Partenheimer, noting that the clearest fix—the use of electronic data—has been slowed by negotiations with international partners. Congressional investigators claim the postal service only received such data on about 30 percent of all international packages, leaving nearly 300 million packages harder to screen in 2017.