China is making moves to fortify their northern border with Russia as the country becomes their leading source of imported cases of coronavirus, according to The Associated Press.

The virus, which is believed to have originated in China, has been appearing less frequently after the government took aggressive mitigation measures, according to numbers reported by the Chinese government.

But on Monday, China’s northeastern border province of Heilongjiang reported 79 new coronavirus cases, all Chinese citizens returning home from Russia. Mongolia reported another 13 cases traced back to Russia, according to Reuters.

ADVERTISEMENT

Chinese officials have ramped up security in Suifenhe, a city in Heilongjiang, adding a checkpoint into Russia and reducing train travel. Citizens of Heilongjiang have been told they’d receive cash rewards for reporting instances of illegal immigration from Russia.

“We are facing a truly grave situation in the northeast as represented by Suifenhe,” National Health Commission expert Wang Bin said Monday at a news conference, according to the AP. “Up to now our medical resources in the area have just not been sufficient.”

Foreign Ministry spokesman Zhao Lijian told Reuters that both Russia and China should be putting in resources to fortify their long border. Zhao noted that there are about 100,000 Chinese nationals living in Russia.

“This responsibility must be shouldered by both sides to uphold order in the border area,” Zhao said.

As of Tuesday, China had reported 82,249 coronavirus cases and 3,341 deaths, though the accuracy of those reports has been contested.