WASHINGTON -- A top US diplomat warned North Korea on Thursday against taking any "ill-advised" action in light of its veiled threats to resume nuclear and long-range missile tests.

David Stilwell, US assistant secretary of state for East Asian and Pacific affairs, made the remark as North Korea has threatened to take a "new way" unless the US offers concessions in their stalled denuclearization negotiations before the end of the year.

Washington has urged Pyongyang to stick to its commitment to cease nuclear and long-range missile tests, saying they would be counterproductive to efforts to reach a deal exchanging North Korea's denuclearization for US concessions.

"Threats are threats. We've heard threats before," Stilwell said during an event at the Center for Strategic and International Studies, when asked about the possibility of a North Korean intercontinental ballistic missile launch.

"(President Donald Trump) has said he wants to work with North Korea," he continued. "He wants to help build their economy. But there's also the reminder that we can't have any more of this unfortunate, ill-advised behavior, and that hasn't changed. That position is the same."

The last time North Korea launched an ICBM was in November 2017. Tensions ran high at the time as the North continued to test it nuclear and ballistic missile programs and hurled insults back and forth with the US president.

Trump and North Korean leader Kim Jong-un have had three meetings since June 2018, but the negotiations have stalled due to wide gaps over how to match Pyongyang's denuclearization steps with Washington's offers of sanctions relief and security guarantees.

On Wednesday the US convened a UN Security Council session to discuss the North's recent short-range missile launches and possible future provocation.

North Korea's foreign ministry later issued an angry statement saying the move gave the regime "decisive help in making up our mind clearly on which way we will take."

Invoking China and Russia, two countries that have backed UN sanctions against Pyongyang despite their traditionally friendly ties with the North, Stilwell said, "A nuclear North Korea is not something anybody really wants and a long list of UN Security Council resolutions support that."

On China, he added that the US across decades "mostly shrugged at" its proliferation of nuclear and missile technology to North Korea, Pakistan, Iran and other countries.

He also offered his praise regarding South Korea's decision to host the US missile defense system, THAAD, in 2017 despite strong opposition from China.

"Despite the pressure, both economic and otherwise, the Korean government did the right thing and stood up in the face of this thing, at great economic cost, too," Stilwell said, referring to China's economic retaliation against South Korea. "That's an example, I think, other countries should look at." (Yonhap)