The letter, obtained by CNN, calls the "Key Resolve" and "Foal Eagle 16" joint military operations, the largest to date
, "aggressive" and directed toward the DPRK, an acronym for North Korea used by the regime.
The letter, written by North Korea's Permanent Representative, Ambassador, JA Song Nam, and addressed to the the president of the Security Council, Ismael Abraao Gaspar Martins, alleges that the operations are a "beheading operation" aimed to remove the supreme leadership of the DPRK and "bring down its social system."
Previous attempts by North Korea to convene the Security Council have failed.
Earlier this month the regime threatened a preemptive nuclear strike
over the war games, which are held annually but have this year been ramped up to include 300,000 South Korean troops and at least 17,000 U.S. forces.
The two exercises will run until April 30. "Foal Eagle" will involve ground, air, naval and special operations forces from both militaries.
The request comes after the Security Council, including North Korea's longstanding ally China, voted on tougher sanctions
on the North in the wake of Pyongyang's purported nuclear
tests earlier in the year.
On Wednesday, the White House announced new sets of sanctions on the regime, independent of the U.N. restrictions.
In response, Chinese Ministry of Foreign Affairs spokesman Lu Kang told journalists at a briefing Thursday that Beijing opposes unilateral sanctions "by any country" and "any measures that might escalate tensions on the (Korean) peninsula."
He said that Beijing has emphasized that "any country that imposes unilateral sanctions should not harm China's interests."
In the letter to the Security Council, the ambassador suggested that the body was obliged by the U.N. Charter to take the matter under consideration, and that a failure to do so would undermine its credibility.
Articles 34 and 35 of the U.N. Charter
allow the Security Council to investigate "any dispute, or any situation which might lead to international friction," and gives member states the right to refer such situations to the attention of the Council.
The letter also references the U.N.'s "dealing with the DPRK's so-called 'human rights situation'" and suggests that addressing the U.S.-South Korean joint operations more crucial to "maintaining international peace and security" than focusing on North Korea's human rights record.
Human rights dismissed
The letter comes shortly after North Korea announced that a U.S. student, Otto Frederick Warmbier, had been sentenced to 15 years
of hard labor after accusing him of removing a political banner from a hotel.
The sentence against the University of Virginia student is "unduly harsh," State Department spokesman Mark Toner said, calling for his release.