One of Russia's leading telecommunications companies has reportedly secured a contract with one of the world's most exclusive buyers: North Korea.

TransTeleKom, a conglomerate operated by Russia's state-owned railroad company that boasts one of the biggest fiber optics networks on Earth, has begun providing internet service to Russia's reclusive neighbor, according to a report by North Korea monitoring group 38 North. The move was uncovered as the U.S. leads an international campaign to isolate North Korea diplomatically and economically over leader Kim Jong Un's refusal to abandon his nuclear and ballistic weapons programs.

Related: Who is Kim Jong Un's wife? You know Melania Trump, meet North Korea's first lady, Ri Sol Ju

With U.S. pressure mounting on China, North Korea's greatest ally and owner of what was previously its only point of access to the internet, Pyongyang may have reached out to Moscow for fear that Beijing would cave to Washington's interests, said Martyn Williams, who runs the North Korea Tech blog and authored the 38 North report.

"I'm sure the North Koreans saw the pressure on China and realized they could lose the existing link at any moment," Williams told Newsweek.

Using information gathered by internet routing databases, Williams was able to determine that the new connection first appeared just after 5 a.m. ET Sunday, which would have been seen in Pyongyang on Sunday evening. TransTeleKom, which is believed to have reached North Korea via the Friendship Bridge that links it to Russia, joins China's state-owned Unicom as the only companies providing web access to a country of 25 million people, but one with few internet users.

The state wields near absolute control over the flow of information in North Korea, and internet access is generally limited to universities, major companies, foreigners with smartphones, government departments and the military's cyberwarfare division. By bolstering the country's bandwidth with a new international provider, Williams said it's possible that North Korea may have just made its internet stronger and faster than ever before.

Since taking power after his father's death in 2011, Kim Jong Un has continued his predecessor's legacy of modernizing the country's technology sector, including the expansion of the cellular network, distance learning systems and integrated circuit cards for banking and public transportation, Williams said. He has also rapidly advanced its military prowess, ordering the country's first two intercontinental ballistic missile tests in July and its sixth nuclear weapons test last month.

North Korea has argued it needs nuclear weapons to deter an invasion, but its moves have angered many foreign countries. President Donald Trump and Kim have engaged in an escalating stand-off of insults and threats in recent months, and the Republican leader ordered a direct cyber assault on hackers tied to North Korea on Saturday, The Washington Post reported.

TransTeleKom was not immediately available to speak when reached for comment by Newsweek, but a company spokesperson told The Financial Times Monday that the Russian firm "has historically had a backbone network interface with North Korea under an agreement with Korea Posts and Telecommunications Corp. struck in 2009."

While China has opted to side more closely with Russia than the U.S. in the ongoing nuclear crisis between Pyongyang and Washington, Beijing has abided with U.S.-led sanctions at the U.N. China’s Ministry of Commerce announced Thursday that all North Korean businesses would have to close within 120 days in accordance with the latest sanctions adopted September 11 by the U.N. Security Council, and scores of North Korean workers have begun leaving the country, Reuters reported Monday.