WASHINGTON -- A nuclear test by North Korea would constitute a "grave escalatory action" that will be met by serious consequences, a state department spokesperson said Wednesday.

Vedant Patel, principal deputy spokesperson for the department, insisted the US has a "number of tools" to hold North Korea accountable for any future provocations.

"A seventh nuclear test, should it happen, would constitute a grave escalatory action and seriously threaten regional stability, international stability, security in the region, and it would also undermine the global non-proliferation regime and efforts that are being undertaken," he said in a daily press briefing.

Pyongyang conducted its sixth and last nuclear test in September 2017. US officials, including state department press secretary Ned Price, have said the North may conduct its seventh nuclear test "at any time."

Patel said the US had a range of tools to hold North Korea accountable, despite its failed attempt earlier in the month at the UN Security Council to impose new UN sanctions on the North.

"I am, of course, not going to read out specifically the various tools in our tool belt that we have to hold the DPRK accountable," he said, referring to North Korea by its official name, the Democratic People's Republic of Korea. "But we have a number of tools available."

Patel also called on China and Russia, both veto power-wielding permanent members of the UNSC and friendly nations to North Korea, to hold Pyongyang accountable when necessary.

Beijing and Moscow have blocked at least three US-led efforts this year to impose fresh UNSC sanctions on North Korea, including the latest attempt this month that followed a series of North Korean missile tests.

"It is, of course, our hope that they will join us in holding the DPRK accountable, but even as recently as earlier this month, we did not see that from the PRC and Russia and instead we saw parroting of disinformation that the US provocations was somehow behind these launches, which is just absolutely not true," said Patel. (Yonhap)