The United Nations Command (UNC) said Tuesday that it could not "definitively" determine whether North Korea started a recent exchange of gunfire with South Korea intentionally or by mistake but found that both sides violated the armistice agreement.

The US-led command, which administers the DMZ and enforces the armistice that halted the 1950-53 Korean War, came to the conclusion after a weekslong investigation into the May 3 incident, where four bullets from the North hit a South Korean guard post, leading South Korean troops to return fire.

According to the investigation, North Korea committed the violation as it fired four rounds of 14.5-millimeter small arms from its guard post located on the northern side of the inter-Korean border at a South Korean guard post.

"However, the investigation was unable to definitively determine if the four rounds were fired intentionally or by mistake," UNC said in a release uploaded on its Facebook page.

The command invited the North Korean military to provide information on the case, and the North acknowledged receipt of the request. But it has not offered a formal response, UNC added.

South Korea also violated the armistice by responding "with two volleys of gunfire" toward North Korea, according to UNC.

"Based on the investigation's comprehensive findings, UNC personnel will engage in follow-on discussions with both sides to encourage an implementation of measures to prevent a recurrence of Armistice violations," the command said.

Noting that the armistice agreement is meant to minimize the risk of incidents such as gunfire exchange, UNC said it will continue to identify and implement ways to improve conditions for peace and stability on the Korean Peninsula.

Following the incident, UNC dispatched a multinational special investigation team for a probe, which was observed by the Neutral Nations Supervisory Commission to ensure transparency and fairness, the command said, adding that the South Korean military fully cooperated with the investigation.     

Earlier, South Korean military authorities said they believe the incident was not an intentional provocation based upon evidence secured from various intelligence sources.

On the day of the incident, US Secretary of State Mike Pompeo also said that he believes the incident was "accidental."

It was the first exchange of gunfire between South and North Korea in years. Under the Comprehensive Military Agreement signed in September 2018, the two Koreas agreed to halt all hostile acts against each other, a move aimed at reducing tensions and building trust.

The DMZ, which is about 250 kilometers long and 4 km wide, is one of the world's most heavily fortified borders and has often been a flashpoint between the rival Koreas, though South Korea has been pushing to turn it into a global peace zone. (Yonhap)