SEOUL—South Korea on Monday afternoon test-fired artillery from an island North Korea attacked last month, defying North Korean threats of another attack and asserting its rights in a maritime area it has controlled since the Korean War of the 1950s.

North Korea didn't immediately respond to the South's artillery drill, which began shortly after 2 p.m. local time (midnight Eastern time) at a marine outpost on Yeonpyeong Island.

The two Koreas have been drawn to the brink of open fighting by North Korea's apparent effort to redraw the maritime boundary near the island and four others controlled by South Korea in the Yellow Sea off the countries' west coast.

The prospect that the two Koreas' border dispute could escalate prompted an emergency meeting of the United Nations Security Council on Sunday in New York. But the nations on the council didn't agree on a statement addressing the dispute. China was blocking a statement that included wording that blamed North Korea for the attack on Yeonpyeong Island last month that set off the current crisis.

The Security Council met at Russia's request, underscoring pressure applied by Moscow and Beijing on Seoul to cancel the test.