China's nuclear envoy in South Korea amid talk of Trump action against North Korea

Seoul/Tokyo: A Chinese envoy held talks in South Korea on Monday on North Korea`s increasingly defiant weapons programme as a U.S. Navy strike group headed to the region amid concerns that Pyongyang may be preparing a fresh nuclear test.

North Korea marks several major anniversaries this month and often marks the occasions with major tests of military hardware. 

The possibility of U.S. military action against North Korea in response to such tests gained traction following last week`s strikes against Syria. 

Previously, Washington has leaned toward sanctions and pressure to deter North Korea, but comments from U.S. President Donald Trump`s top aides at the weekend suggested that position may be hardening.

The U.S. Navy strike group Carl Vinson canceled a planned trip to Australia and was moving toward the western Pacific Ocean near the Korean peninsula as a show of force, a U.S. official told Reuters over the weekend. "We feel the increased presence is necessary," the official said.

The events took place after Trump and China`s President Xi Jinping held a summit meeting in Florida, where Trump pressed his counterpart to do more to curb North Korea`s nuclear programme.

China is North Korea`s main diplomatic and economic ally.

There were no immediate details on what was discussed between China`s Special Representative for Korean Peninsula Affairs, Wu Dawei, and his South Korean counterpart. But the talks were expected to focus on the North`s nuclear issue, the South Korean foreign ministry said earlier. 

It was also the first visit to South Korea by a senior Chinese official since the planned deployment of the U.S. THAAD missile defense system led to a diplomatic row between Beijing and Seoul.

U.S. Secretary of State Rex Tillerson said the U.S. military strike against Syria over its alleged use of chemical weapons was a warning to other countries including North Korea that "a response is likely" if they pose a danger. 

"(Chinese) President Xi (Jinping) clearly understands, and I think agrees, that the situation has intensified and has reached a certain level of threat that action has to be taken," Tillerson said on CBS`s Face the Nation. 

North Korea has sounded a note of defiance, calling the U.S. strikes against Syria on Friday "an unforgivable act of aggression" that showed its decision to develop nuclear weapons was "the right choice." 

In Tokyo, the feasibility of U.S. military action was downplayed, while South Korea said the focus remained on deterrence and readiness. 

"It probably is not realistic for the U.S. to attack North Korea," a Japanese defence ministry source said. "If America says it is going to attack, both Japan and South Korea will probably put a stop to it," said the source who declined to be identified.

A senior Japanese military source added: "If the U.S. military was to attack, there could be a request to Japan for rear-guard logistics support but there has been no talk of such preparations."

South Korean and U.S. forces are also involved in annual joint military drills that run until the end of April. The North calls the drills preparations for war against it. 

Several North Korean anniversaries in April could be an opportunity for Pyongyang to conduct nuclear or missile tests, South Korean defence ministry spokesman Moon Sang-kyun said.

North Korea has invited a large number of foreign media representatives to Pyongyang this week, likely to cover the so-called "Day of the Sun" birth anniversary on April 15 of the state founder Kim Il Sung.

Moon did not directly respond to a question about the possibility of a U.S. military strike against the North.

"Considering the possibility of North Korea`s strategic provocations such as a nuclear test and missile launches, we have in place deterrence to the North`s provocation and all readiness against them," he told a briefing on Monday. 

The Unification Ministry also played down the possibility of U.S. military strikes against the North, saying it was confident Washington is fully behind the South`s policy of using dialogue and pressure to resolve the North Korea situation, not force.

Senior envoys of South Korea, Japan and the United State on the North Korea nuclear programme will soon meet to discuss their coordinated response, the South`s foreign ministry said.

North Korea launched a ballistic missile on Wednesday that flew a short distance before spinning out of control and crashing into the sea, the latest of a number of missile tests defying U.N. sanctions. 

The North is also seen to be ready to conduct its sixth nuclear test at any time, with movements detected by satellites at its Punggye-ri nuclear test site.