In this photo provided by U.S. Forces Korea, trucks carrying U.S. missile launchers and other equipment needed to set up the Terminal High Altitude Area Defense (THAAD) missile defense system arrive at the Osan air base in Pyeongtaek, South Korea, Monday, March 6, 2017. The U.S. military has begun moving equipment for the controversial missile defense system to ally South Korea. The announcement Tuesday by the U.S. military comes a day after North Korea test-launched four ballistic missiles into the ocean near Japan.  (U.S. Force Korea via AP)
In this photo provided by U.S. Forces Korea, trucks carrying U.S. missile launchers and other equipment needed to set up the Terminal High Altitude Area Defense (THAAD) missile defense system arrive at the Osan air base in Pyeongtaek, South Korea, Monday, March 6, 2017. The U.S. military has begun moving equipment for the controversial missile defense system to ally South Korea. The announcement Tuesday by the U.S. military comes a day after North Korea test-launched four ballistic missiles into the ocean near Japan. (U.S. Force Korea via AP)

SEOUL, South Korea — U.S. missile launchers and other equipment needed to set up a controversial missile defense system have arrived in South Korea, the U.S. and South Korean militaries said Tuesday, a day after North Korea test-fired four ballistic missiles into the ocean near Japan.

The plans to deploy the Terminal High-Altitude Area Defense system, or THAAD, within this year have angered not only North Korea, but also China and Russia, which see the system’s powerful radars as a security threat.

China responded quickly, saying it will take “necessary measures” to protect itself and warning that the U.S. and South Korea should be prepared to bear the consequences.

Washington and Seoul say the system is defensive and not meant to be a threat to Beijing or Moscow. The U.S. military said THAAD can intercept and destroy short and medium-range ballistic missiles during the last part of their flights.

“Continued provocative actions by North Korea, to include yesterday’s launch of multiple missiles, only confirm the prudence of our alliance decision last year to deploy THAAD to South Korea,” Adm. Harry Harris, head of the U.S. Pacific Command, said in a statement.

Some South Korean liberal presidential candidates have said that the security benefits of having THAAD would be curtailed by worsened relations with neighbors China and Russia.

“China firmly opposes the deployment of THAAD,” Chinese Foreign Ministry spokesman Geng Shuang said at a regular briefing Tuesday. “All consequences entailed from that will be borne by the U.S. and (South Korea). We once again strongly urge the relevant sides to stop the process of deployment and refrain from going further down that wrong path.”

State Department acting spokesman Mark Toner said THAAD is a system being put in place because of North Korea’s provocative behavior.

“We have been very clear in our conversations with China that this is not meant to be a threat, and is not a threat to them or any other power in the region,” he told reporters in Washington.

Asked about U.N. reaction to the dispute over THAAD’s deployment, U.N. deputy spokesman Farhan Haq said: “We hope that efforts will be stepped up to find a path to reduce tensions and to work for denuclearization of the Korean Peninsula.”

China’s condemnation of South Korean plans to deploy THAAD has triggered protests against a South Korean hypermarket chain, Lotte Mart, whose parent company agreed to provide one of its golf courses in southern South Korea as the site of THAAD. Visits by South Korean film stars and singers have been canceled and shipments of South Korean cosmetics have been held up at customs.

Experts say China could also send Chinese coast guard ships to escort fishing boats into waters claimed by South Korea, dispatch military aircraft and ships into South Korean air and sea space, and suggest that it might do less to restrain North Korea from provocative behavior.

Russia has supported China’s opposition to the system. Militarily, Russia and China could deploy more missiles, especially those with maneuverable warheads to overwhelm THAAD, along with the use of decoys and attempts to jam the system, analysts say.