WASHINGTON (AP) — South Korea’s top diplomat said Monday that North Korea has completed preparations for a new nuclear test and that only a political decision by the country’s top leadership can prevent it from going forward.

After talks with Secretary of State Antony Blinken in Washington, South Korean Foreign Minister Park Jin said the North would pay a price if it goes ahead, as feared, with what would be its seventh nuclear test in the coming days.

“North Korea has completed preparations for another nuclear test and I think only a political decision has to be made,” Park said. Prior to Monday, U.S. and South Korean officials had said only that the North was nearing completion of such preparations.

“If North Korea ventures into another nuclear test, I think it will only strengthen our deterrence and also international sanctions," Park said. “North Korea should change its mind and make the right decision.”

Apart from sanctions, Park did not say what that price the North would pay or outline how the deterrence policy would change, but Blinken said the United States and treaty allies South Korea and Japan could adjust their military postures in response.

“We’re preparing for all contingencies this in very close coordination with others and we are prepared to make both short and longer-term adjustments to our military posture,” Blinken said. He added that in addition, “the pressure will be sustained, it will continue and, as appropriate, it will be increased.”

Both Park and Blinken men stressed the door to negotiations without any preconditions remains open for North Korea. But Blinken, repeating comments from numerous U.S. officials in recent days, lamented that North Korea continues to ignore overtures for dialogue.

On Sunday, North Korea test-fired what appeared to be artillery shells toward the sea, according to South Korea’s military, days after North Korean leader Kim Jong Un called for greater defense capability to cope with outside threats.

The North’s artillery tests draw less outside attention than its missile launches, of which it has conducted more so far this year than in any previous year. But its forward-deployed long-range artillery guns are a serious security threat to South Korea’s populous metropolitan region, which is only 40-50 kilometers (25-30 miles) from the border with North Korea.

The suspected artillery launches were the latest in a spate of weapons tests by North Korea this year in what foreign experts call an attempt to pressure its rivals Washington and Seoul to relax international sanctions against Pyongyang and make other concessions.

In March, North Korea test-launched an intercontinental ballistic missile capable of reaching the mainland U.S. in breach of a 2018 moratorium on big missile tests.

A possible new nuclear test by North Korea would be the seventh of its kind. Some experts say North Korea will likely use the test to build warheads to be mounted on tactical nuclear weapons aimed at hitting targets in South Korea.

Matthew Lee, The Associated Press