Moscow may be looking to take advantage of the nuclear standoff between Pyongyang and the international community. As cracks deepen in the decades-old friendship between China and North Korea amid increasing U.S. pressure, Russian President Vladimir Putin stands ready to fill Beijing's shoes. "Russia (has) begun quietly laying the groundwork that would strengthen its ties to North Korea, thus increasing its global political leverage should it need it," analysts at political intelligence firm Stratfor explained in a May 5 report, referring to Putin's strained ties with the West.

This undated picture released from North Korea's official Korean Central News Agency (KCNA) on May 5, 2017 shows North Korean leader Kim Jong-Un inspecting the defence detachment on Jangjae Islet and the Hero Defence Detachment on Mu Islet. STR | AFP | Getty Images

Both countries share a long history of ideological and economic relations — in 2014, Moscow wrote off 90 percent of Pyongyang's $11 billion debt from the Soviet-era — but recent projects indicate an even cozier relationship. A new ferry service between Rajin and Vladivostok is due to begin on May 8 that's expected to carry up to 200 passengers and 1,000 ton of cargo six times a month. Meanwhile in April, Russian military hardware was seen transported to the country's border with North Korea but the Kremlin claimed the action was part of pre-planned military exercises, Reuters reported. "There is little doubt that Russia is making sincere attempts at building a partnership with North Korea," Russia-Korea analyst Anthony Rinna said in an April 14 note published on the Institute of Asia and Pacific Studies at the University of Nottingham. "The idea that Russia is once again superseding China as North Korea's major international patron bodes well when viewed through the prism of North Korea's Cold War-era tactics of playing China and the USSR off of each other." In March, officials also agreed to expand North Korean labor immigration to Russia. Tens of thousands North Koreans are believed to be living in the Eurasian country, many of whom are forced laborers sent to bring in overseas revenue for Kim Jong-un's regime, according to human rights groups.