US and South Korea begin four-day air drills with 230 aircraft and 12,000 troops, in a move denounced by Pyongyang.
North Korea warned the United States any imposition of a maritime blockade would be an act of war that would push the current standoff towards nuclear confrontation.
Discussion of a possible American sea blockade off the Korean Peninsula has emerged in media reports and academic circles in recent weeks, further ratcheting up tensions between Washington and Pyongyang.
The threat of nuclear war between the arch enemies has grown more real since US President Donald Trump took office in January. He has threatened to “totally destroy” North Korea – demanding it surrender its nuclear and missile programmes.
Pyongyang has baulked at the demand saying it needs a functioning “state nuclear force” to prevent “invasion and plunder” by the United States, which has 28,500 troops stationed in neighbouring South Korea, a legacy of the 1950-53 Korean War.
“The gang of Trump … is driving the situation on the Korean Peninsula more and more close to the brink of war, acting recklessly without any sense of reason,” the official Korean Central News Agency (KCNA) said in a Thursday report.
“A naval blockade is an act of wanton violation of the sovereignty and dignity of an independent state, and an act of war of aggression which cannot be tolerated.”
On Friday, US Secretary of State Rex Tillerson will chair a special meeting of the UN Security Council to discuss North Korea’s nuclear and missile programmes.
KCNA described the meeting as a “desperate measure plotted by the US”.
In an unusual step towards diplomacy, Tillerson on Wednesday said the US was ready to sit down and talk about the North’s denuclearisation “without preconditions”.
However, US National Security Adviser HR McMaster later dismissed Tillerson’s proposal, suggesting reporting on the secretary of state’s comments was incorrect.
On Thursday, Russian President Vladimir Putin praised Tillerson’s overture towards North Korea’s Supreme Leader Kim Jong-un.
“This is a very good sign that shows that the American leadership is moving towards an awareness of reality,” Putin said during a press conference in Moscow.
“We believe that both sides need to stop aggravating the situation. North Korea is a closed country. It’s enough for one firing [of a missile] from North Korea and the consequences will be catastrophic.”
Putin said Pyongyang feels threatened by Washington and “sees no other way for survival other than developing weapons of mass destruction”.
North Korea tested its most advanced intercontinental ballistic missile on November 29, which it said could put all of the United States within range.
For its part, the US has said “all options were on the table” in dealing with North Korea, including military action.
China and the United Nations also weighed in on the intensifying dispute on Thursday.
Chinese President Xi Jinping said war cannot be started over the nuclear stalemate.
“The peninsula issue must, in the end, be resolved via dialogue and consultation,” Xi was quoted as saying by state media.
UN Secretary-General Antonio Guterres said Friday’s Security Council would highlight the need for diplomacy to resolve the issue.
“The worst possible thing that could happen is for us all to sleepwalk into a war,” said Guterres.