The American government "secretly expelled" two Chinese officials after they breached a "sensitive" military base in Virginia, the New York Times reported Sunday.

According to the Times, U.S. officials believe at least one of the officials expelled is a Chinese intelligence officer using fraudulent diplomatic as cover. The incident leading to their expulsion happened in September. Neither the U.S. nor China has publicly acknowledged the incident.

From the Times:

The Chinese officials and their wives drove up to a checkpoint for entry to the base, said people briefed on the episode. A guard, realizing that they did not have permission to enter, told them to go through the gate, turn around and exit the base, which is common procedure in such situations.



But the Chinese officials instead continued on to the base, according to those familiar with the incident. After the fire trucks blocked them, the Chinese officials indicated that they had not understood the guard's English instructions, and had simply gotten lost, according to people briefed on the matter.



However, American officials were skeptical that "that the intruders made an innocent error," according to the Times.

The incident took place on a "sensitive installation" near Norfolk, Virginia, where special operations units are housed. The Navy's SEAL Team Six has its headquarters in the area, the Times reported.

The expulsion marks the first time that Chinese officials have been expelled from the U.S. in more than 30 years, the last such occurrence coming in 1987.

The incident comes at a time when the Trump administration is becoming increasingly concerned about Chinese espionage efforts as President Donald Trump battles an economic and political war with the Communist nation.

China has not yet retaliated against the U.S. for the expulsions, which the Times reported may indicate that Chinese officials believe their two colleagues may have gone too far in trying to spy for Beijing.