International aid workers are expected to have a greater understanding within days of how the spread of the coronavirus has affected North Korea, after Russia succeeded in shipping diagnostic test kits into the country.

The Russian government was able to get diagnostic test kits on a flight returning to North Korea from Pyongyang earlier this week after evacuating foreign diplomats and other travelers, a worker with an American nongovernmental organization tells U.S. News on the condition of anonymity, due to the sensitive nature of the person's work.

"If they get the tests to run on their machines, we should start to hear about confirmed cases of COVID-19 in a few days," says the worker, who has extensive experience in North Korea.

The country, under widespread lockdown in response to the global pandemic, has become one of the most troubling blind spots in the international response to the spread of the coronavirus. Little is known about North Korea's current capabilities to determine the potential spread of the virus and its capacity to test its citizens on a nationwide scale. That means global health officials have virtually no information about how the country has been affected by the virus that has roiled neighboring China and South Korea.

Multiple international aid groups, made aware of the plans for the flight – which was ultimately delayed a week – have been working to get test kits and other medical supplies onto the Air Koryo return flight. It's unclear whether any other organizations were successful.

But the Russian tests will provide critical information at a time international health workers have struggled to better understand the situation in North Korea. The traditionally closed-off country has enforced limits on domestic and foreign travel at levels that appear to eclipse its responses to the SARS, MERS and Ebola outbreaks.

North Korea has not acknowledged any confirmed cases of the coronavirus within its borders, while neighboring South Korea documents more than 7,000 cases and China reports almost 5,000 deaths as a result. Leader Kim Jong Un has attempted to demonstrate that his country is taking the spread of the virus seriously, including allowing the release of photos that show military service members wearing preventative medical masks. North Korea has also launched two rounds of short-range missiles in recent weeks, an effort analysts say is designed to show it remains a potent threat despite the health crisis.

Many with experience working with North Korea's public health system tell U.S. News that it's as likely the central government is aware of cases and has refused to release that information publicly as it is that Pyongyang hasn't had the capability to determine whether someone demonstrating symptoms has the coronavirus or the common flu. It's also possible the central government's crackdown has succeeded at preventing the spread of the virus there.

"The main priority really is to make sure DPRK is well equipped to avoid any spread of the disease, the virus," Fabio Forgione, Doctors Without Borders' head of mission for DPRK – an acronym for North Korea's official name – said in a recent interview. "At the moment, our feeling is they're really trying to work on prevention. They have in place all the right strategies to try to tackle and prevent the spread of the virus."

Multiple aid groups, including Doctors Without Borders, have told U.S. News their main goal has been shipping supplies into China, where local authorities have previously been effective at getting them into North Korea, a traditional ally.

Despite widespread closures along North Korea's borders, sources tell U.S. News one bridge technically remains open to outside traffic, connecting the Chinese city of Dandong to Sinuiju on the North Korean side. The main problem, however, is getting supplies that far into China amid that country's own travel restrictions.

Meanwhile, international concern about the extent of the virus' spread in North Korea continues to grow.

"Global health security is only as good as the weakest link," says Kee Park, director of the North Korea Program at the Korean American Medical Association and a lecturer on global health and social medicine at Harvard University.