The United Nations Security Council is to meet on Monday to discuss the next action against the reclusive state.
"There is a long way yet to go to make North Korea feel the kind of pressure that they clearly need to feel in order to change their calculus". North Korea has described the recent atomic bomb test as a deterrent move and a gift for Washington.
The tensions have weighed on global markets, but yesterday there was some relief among investors that North Korea did not conduct another missile test over the weekend when it celebrated its founding anniversary.
"We should treat that claim with scepticism, but the House must be under no illusion that this latest test marks another perilous advance in North Korea's nuclear ambitions".
Her spokesman, Steffen Seibert, says Merkel spoke by phone Thursday with Xi and both expressed great concern about the situation in North Korea.
"It shows the United States commitment if North Korea attacks South Korea or Japan", said political science professor, Dr. Malcolm Koch.
With the four additional launchers installed, U.S. Forces Korea will have a fully operational THAAD battery at its base in Seongju.
But Putin made clear that Russian Federation was opposed to further interdictions, and while China - North Korea's patron and closest political and economic partner - has yet to be drawn on the issue, it tends to resist placing pressure on Pyongyang.
South Korean President Moon Jae-In urged Russian Federation on Wednesday to cooperate over cutting oil supplies to North Korea but President Vladimir Putin appeared to pour cold water on the idea.
In an interview with Russia's TASS News Agency, Moon said, "Seoul will respond to it in the most decisive manner, particularly by toughening sanctions, increasing pressure and strengthening its own military capabilities".
The official, speaking on condition of anonymity, said there was grave risk that North Korea could "miscalculate" the US response to its weapons testing and warned Pyongyang not to under-estimate Washington's resolve.
Chinese foreign ministry spokesman Geng Shuang also reiterated Beijing's opposition to South Korea's deployment of the US Terminal High-Altitude Area Defence System, also known as THAAD, which is meant to protect against North Korean missile attacks. The deployment has drawn strong objections from China, which believes the system's radar could be used to look deeply into its territory and will upset the regional security balance.