A Japan Self-Defense Forces soldier takes part in a drill to mobilize their Patriot missile unit in response to a recent missile launch by North Korea, on the outskirts of Tokyo on August 29, 2017.

:: South Korea said on Monday it was preparing fresh military drills with its ally the United States and ramping up its ballistic missile defenses in response to North Korea’s sixth and most powerful nuclear test a day earlier.

The United Nations Security Council was set to meet later on Monday to discuss fresh sanctions against the isolated regime. US President Donald Trump had also asked to be briefed on all available military options, according to his defense chief.

South Korea’s air force and army conducted exercises involving long-range air-to-surface missiles and ballistic missiles on Monday, the joint chiefs of staff said in a statement. More drills were being prepared with US forces in the South, it said.

The South’s environment ministry will also announce on Monday its approval of an environmental assessment report for the deployment of a controversial US anti-missile defense system, a ministry official told Reuters. Seoul said in June it would hold off installing the remaining components of the Terminal High Altitude Area Defense (THAAD) system until it completed an assessment of its impact on the environment.

North Korea said an advanced hydrogen bomb for a long-range missile was tested on Sunday, prompting the warning of a “massive” military response from the United States if it or its allies were threatened. “We are not looking to the total annihilation of a country, namely North Korea,” US Defense Secretary Jim Mattis said after meeting Trump and his national security team. “But as I said, we have many options to do so.”

Trump has previously vowed to stop North Korea developing nuclear weapons and said he would unleash “fire and fury” if it threatened US territory. That prompted the North to threaten to fire missiles towards the US Pacific territory of Guam, although it has since appeared to back away from that threat.

Tougher sanctions?

Despite the tough talk, the immediate focus of the international response was expected to be on tougher economic sanctions against Pyongyang. Diplomats have said the UN Security Council could now consider banning Pyongyang’s textile exports and the North’s national airline, stop supplies of oil to the government and military, prevent North Koreans from working abroad and add top officials to a blacklist to subject them to an asset freeze and travel ban.

South Korean President Moon Jae-in and Japanese Prime Minister Shinzo Abe agreed on Monday to pursue stronger UN sanctions. “Both heads of state agreed to cooperate closely with each other and the United States and shared the understanding there must be the most powerful sanctions and pressure applied on North Korea,” presidential Blue House spokesman Park Su-hyun told a media briefing after the two leaders spoke by phone.

The aim of stronger sanctions was to draw North Korea into dialogue, he said. In a series of tweets on Sunday, Trump appeared to rebuke South Korea for that approach.

“South Korea is finding, as I have told them, that their talk of appeasement with North Korea will not work, they only understand one thing!” Trump said on Twitter. Still, Trump’s response was more orderly and less haphazard than he had offered to other provocations by North Korea.