Officials from South Korea and the United States have issued warnings that a potential visit by Russian President Vladimir Putin to North Korea, anticipated to happen this month, might deepen military ties and infringe upon United Nations Security Council resolutions.

South Korea's foreign ministry stated on Friday that Vice Foreign Minister Kim Hong-kyun had an urgent phone call with US Deputy Secretary of State Kurt Campbell. During this call, they agreed that Putin's visit should not lead to further military cooperation between Russia and North Korea.

"While closely observing related developments, both parties agreed to firmly respond through close cooperation to North Korea’s provocations against South Korea and actions that would raise regional tensions," the ministry's statement read.

Campbell affirmed ongoing cooperation to address potential regional instability and issues arising from the visit.

Speculation about the trip started on Monday when Russia's Vedomosti newspaper reported that Putin would visit North Korea and Vietnam in the coming weeks. On Thursday, Kremlin spokesperson Dmitry Peskov did not specify a date for the potential visit.

"We have the right to establish good relations with our neighbors which should not be of concern to anyone,” Peskov remarked, adding that North Korea is a "friendly nation" for Russia and they will continue to develop bilateral relations. "The potential for the development in our relations is vast," he stated.

Weapons to target Ukraine

The US claims that North Korean-made missiles and artillery shells have been used by Russia during its war with Ukraine. Although Moscow and Pyongyang have denied these allegations, both leaders met in eastern Russia last September and agreed to strengthen cooperation, including military ties.

On Wednesday, Campbell mentioned that the US is well aware of what North Korea has supplied to Russia, stating it had "a significant impact on the battlefield." However, the specifics of what Russia has given in return remained unclear. "Is it hard currency? Energy? Capabilities that allow them to advance their nuclear or missile products? We don't know. But these are concerns we're monitoring closely," he said.

In March, US Director of National Intelligence Avril Haines pointed out that due to the war on Ukraine, Russia had been compelled to make “long-sought concessions” to North Korea, China, and Iran, potentially undermining long-standing non-proliferation norms.

Haines did not detail her warning, but it potentially suggested that Russia could provide North Korea with military-related technology. Kim Jong Un has been spearheading North Korea’s military modernization, with the country testing various weaponry and launching its first military spy satellite last November.