SEOUL, South Korea — An American missile-defense system deployed to counter growing threats from North Korea has gone into operation in South Korea, officials said on Tuesday.

The installation of the Terminal High Altitude Area Defense battery has roiled the South Korean presidential campaign, partly over questions of who will pay for it, and drawn objections from China, which said the deployment undermined its own missile defense abilities.

The United States and South Korea began installing the radar and other important components of the system, known as Thaad, last week at an abandoned golf course in Seongju, 135 miles southeast of Seoul, after reaching an agreement to deploy it last July.

The system “is operational and has the ability to intercept North Korean missiles” and defend South Korea, said Col. Robert Manning III, a spokesman with the United States military in Seoul, the South Korean capital. His statement was echoed by the South Korean Defense Ministry, whose representative, Moon Sang-gyun, said the battery “has acquired an initial capability to deal with North Korea’s nuclear and missile threat.”