This video released by DPRK Today shows an animated depiction of a missile attack on South Korea by the North. (North Korean propaganda)

North Korea has developed a large-caliber multiple launch rocket system and could use it to strike South Korea as soon as this year, the South’s defense minister said Wednesday.

This comes a day after South Korean officials said they thought that the North was now able to mount a nuclear warhead on a medium-range missile, and after China sharply curtailed trade with its dependent neighbor.

Tensions have been running high in the region since North Korea conducted its fourth nuclear test at the beginning of January, then followed it up with a long-range missile launch.

Current joint U.S.-South Korean military exercises and a looming Workers’ Party Congress in North Korea both have stoked the fire.

South Korea Army’s 130mm multiple rocket launcher is fired during an exercise in the eastern coastal county of Goseong, which borders North Korea, on Monday. (Yonhap/AFP/Getty Images)

Han Min-koo, South Korea’s defense minister, said that North Korea’s recent test firings of 300-millimeter rockets suggested that it had almost completed the development of its multiple launch rocket system.

“Under this assessment, I think North Korea will deploy the 300-mm MLRS as early as the end of this year,” Han told local reporters.

The rockets, which are much cheaper than missiles, are thought to have a range of about 125 miles. Greater Seoul, with a population of almost 26 million people, is just 35 miles from the demilitarized zone that separates North and South Korea.

North Korea recently threatened to “scorch” South Korea’s president’s offices with its “powerful large-caliber multiple-rocket-launching systems.”

Pyongyang has boasted of numerous improvements in its missile and rocket program in recent months, saying that it had road-mobile multiple rocket launchers, which it could deploy quickly and without detection, and that it had tested a solid-fuel rocket engine, another major advance. Its claims have not been independently verified, but Pyongyang is known to be working on its delivery systems.

Separately, the South Korean government said that it thought North Korea had made significant progress toward its goal of miniaturizing a nuclear warhead so it could be mounted on a medium-range Rodong missile.

“We believe they have the ability to mount a nuclear warhead on a Rodong. Whether they will fire it like that is a political decision,” an unnamed official told reporters in Seoul.

The Rodong missile could fire a one-ton warhead as far as 1,250 miles, the official said, putting all of South Korea and most of Japan within range.

North Korea’s state media last month released photos of Supreme Leader Kim Jong Un with what it said was a miniaturized nuclear warhead, but this has not been verified.

Pyongyang has proved it is developing both nuclear weapons and the means to deliver them, but it has not yet been shown that it can put the two together. However, many scientists and U.S. military officials say it is just a matter of time until North Korea masters the technology.

Still, the timing of Seoul’s pronouncements is notable. South Korea is holding general elections next week, and such warnings could help President Park Geun-hye’s conservative ruling party in the polls. It controls more than half the seats in the National Assembly.

But in another sign that the international community is cracking down on North Korea over its recent provocations, China this week announced it would ban imports of coal, iron ore, gold, rare earths and several other minerals from North Korea if they were related to its nuclear or missile programs.

Several North Korean mining companies have been accused of channeling funds directly to weapons programs.

The Ministry of Commerce also said China would no longer allow aviation fuel to be exported to North Korea, in accordance with U.N. Security Council resolutions.

China, which is North Korea’s closest ally and shares a long border with the irascible state, has signed up for tough new sanctions against North Korea after its nuclear and missile tests.

There remains a considerable amount of skepticism about how far China will go in enforcing the sanctions — its big-picture strategic interest is in keeping North Korea stable.

Yoonjung Seo in Seoul and Liu Liu in Beijing contributed to this report.