The one-day firing drills are planned by Tuesday on the same front-line island the North shelled last month as the South's military conducted similar drills. The shelling killed four people on Yeonpyeong Island near the tense sea border.
The North's Foreign Ministry said Saturday that South Korea would face an unspecified "catastrophe" if the drills take place, in a statement carried by the official Korean Central News Agency. The North also said it would strike harder than before.
South Korea says the drills are routine, defensive in nature and should not be considered threatening. The U.S. supports that and says any country has a right to train for self-defense, but Russia and China, fellow permanent members of the U.N. Security Council, have expressed concern.
Russia's Foreign Ministry urged South Korea to cancel to avoid escalating tensions.
The Security Council scheduled emergency closed-door consultations on North Korea for 11 a.m. (1600 GMT) Sunday at Russia's request, said Mark Kornblau, spokesman for the U.S. Mission to the United Nations. The United States holds the council's rotating presidency this month.
Russia's U.N. Ambassador Vitaly Churkin said the Russian government believes the Security Council must send "a restraining signal" to North Korea and help launch diplomatic actions to resolve all disputes between North Korea and South Korea.
China, the North's key ally, said it is firmly against any acts that could worsen already-high tensions on the Korean peninsula. "In regard to what could lead to worsening the situation or any escalation of acts of sabotage of regional peace and stability, China is firmly and unambiguously opposed," Chinese Foreign Ministry spokeswoman Jiang Yu said in a statement Saturday.
China's Vice Foreign Minister Zhang Zhijun also warned in a statement that the situation on the Korean peninsula is "extremely precarious."
Bad weather is preventing the artillery drills over the weekend, but they will be conducted either Monday or Tuesday, a Joint Chiefs of Staff officer said Saturday.
The military was ready to respond to any possible provocation, the officer said on condition of anonymity, citing department rules.
Marines carrying rifles conducted routine patrols Saturday. About 300 residents, officials and journalists remain on Yeonpyeong, but officials from Ongjin County, which governs the island, said they had no immediate plans to order a mandatory evacuation to the mainland.
"North Korea said it will deal the powerful ... blow at us if we go ahead and fire artillery. So residents are getting more restless," said Yoon Jin-young, a 48-year-old islander.
Activists launched balloons containing about 200,000 propaganda leaflets toward the North from the island, which is only about seven miles (11 kilometers) from North Korean shores. The balloons also carried 1,000 $1 bills and DVDs containing information on the North's artillery barrage last month.
Several bloody naval skirmishes occurred along the western sea border in recent years, but last month's assault was the first by the North to target a civilian area since the end of the 1950-53 Korean War. The North does not recognize the U.N.-drawn sea border in the area.
The North claims South Korea fired artillery toward its territorial waters before it unleashed shells on the island last month, while the South says it launched shells southward, not toward North Korea, as part of routine exercises.
A flurry of regional diplomacy was under way to defuse the tensions, with New Mexico Gov. Bill Richardson visiting the North.
A frequent unofficial envoy to the reclusive country, Richardson said he wanted to visit the North's main nuclear complex and meet with senior officials during his four-day trip, though details of his schedule were unclear.
"My objective is to see if we can reduce the tension in the Korean peninsula," Richardson said upon his arrival, according to Associated Press Television News.
Kim reported from Seoul. Associated Press writers Cara Anna in Beijing, Robert Burns in Washington, David Nowak in Moscow and AP Television News cameraman Kim Yong-ho on Yeonpyeong Island contributed to this report.