Unable to make de-escalation progress using conventional diplomatic means at the United Nations, on Monday South Korean President Moon Jae-in proposed that the U.N. Security Council hold serious discussions about imposing an energy and capital blockade on North Korea, by cutting off oil supplies to Kim’s regime coupled with a block of North Korean sources of foreign currency, the South Korean president’s office said. Moon discussed the idea with his Russian counterpart, Vladimir Putin, during a phone call, according to South Korea’s Blue House.

“It’s time for the U.N. Security Council to seriously consider ways to block North Korea’s sources of foreign currency, including a halt to oil supplies to the North and a ban on its exportation of laborers,” the office quoted Moon as saying in the wake of the 6th North Korean nuclear test.

According to Yonhap, the South Korean leader also said Sunday’s nuclear test “was different from past experiments in size and character, and expressed his heightened concern over North Korea’s claim that it was an H-bomb that can fit atop an intercontinental ballistic missile.”

Putin, who is attending a BRICS emerging economies summit in China, sided with his South Korean peer and said that North Korea’s nuclear and ballistic missile programs destroy the international nonproliferation regime and pose a “real threat” to regional peace and stability. He also noted that the leaders at the summit adopted a statement condemning the latest test. Moon underscored his commitment to resolving the North Korean nuclear issue diplomatically and peacefully. Putin, in turn, said the leaders at the summit agreed there is only a diplomatic solution to the problem.

“In order to do that, North Korea must refrain from additional provocations,” Moon was quoted as saying during the 20-minute talks. The leaders agreed to hold further discussions at their summit in Vladivostok, Russia, later this week.