Before the start of business, Just Security provides a curated summary of up-to-the-minute developments at home and abroad. Here’s today’s news.

NORTH KOREA NUCLEAR WEAPONS TEST

North Korea conducted a sixth nuclear test yesterday, according to the Pyongyang regime, marking its sixth nuclear test which was a “perfect success in the test of a hydrogen bomb for an I.C.B.M. [intercontinental ballistic missile],” a televised statement said, Jonathan Cheng reporting at the Wall Street Journal.

North Korea may be preparing to launch another I.C.B.M., South Korean defense ministry official Chang Kyung-soo said today, declining to set out details of the signs of activity detected, the defense ministry also stating that the U.S. would seek to temporarily deploy four more T.H.A.A.D. antimissile launchers to a site in Seongju, south of Seoul. The BBC reports.

An attack on the U.S., Japan or South Korea “will be met with a massive military response,” Defense Secretary James Mattis said yesterday, responding to the latest nuclear test, also calling on North Korea to defuse tensions and warning that while the U.S. is “not looking to the total annihilation” of North Korea, it has “many options to do so.” Michael C. Bender and Brent Kendall report at the Wall Street Journal.

“South Korea is finding … that their talk of appeasement with North Korea will not work, they only understand one thing!” President Trump tweeted yesterday, following the nuclear test, which was the most powerful launch by Pyongyang to date and caused tremors felt in South Korea and China – though it was not clear that it was a hydrogen bomb, as the regime claimed. David E. Sanger and Choe Sang-Hun report at the New York Times.

“We’ll see,” Trump told reporters yesterday in response to a question asking if the administration were planning to attack North Korea and, in a series of tweets, the president took aim at South Korea and warned that the U.S. was considering “stopping all trade with any country doing business with North Korea,” Philip Rucker reporting at the Washington Post.

South Korea conducted a simulated attack on North Korea’s Pungyye-ri nuclear test site today – the site of yesterday’s launch – in a show of force, Justin McCurry reports at the Guardian.

The U.N. Security Council will meet today to discuss North Korea’s nuclear test, called at the behest of U.S., Japan, Britain, France and South Korea, and any new sanctions would build on the eight U.N. Security Council resolutions already leveled against Pyongyang. Michelle Nichols reports at Reuters.

South Korea and Japan “agreed to push for more powerful U.N. sanctions” against North Korea, the spokesperson for South Korea’s presidential office said today, Reuters reporting.

Trump’s threat to cut trade with “any country doing business with North Korea “is neither objective nor fair,” China’s Foreign Ministry spokesperson Geng Shuang said today, the AP reports in rolling coverage.

“The imposed sanctions have not created any positive outcome,” Dmitry Peskov, a spokesperson for Russia’s Kremlin, said yesterday, adding that Russia would take part in “all discussions on North Korea” within the framework of the U.N. Security Council and “in other forms,” Andrey Ostroukh reporting at Reuters.

North Korea’s nuclear test is “profoundly destabilizing for regional security,” U.N. Secretary-General António Guterres said yesterday, according to a statement issued by a U.N. spokesperson. The UN News Centre reports.

North Korean state news agency referred to having electromangentic (E.M.P.) capability yesterday morning, suggesting the ability to overwhelm and shutdown the U.S. electric grid and electronic devices. Peter Landers reports at the Wall Street Journal.

 “I am going to draft a sanctions package to send to the president for his strong consideration,” U.S. Treasury Secretary Steven Mnuchin said yesterday, adding that “people need to cut off North Korea economically,” Rebecca Savransky reports at the Hill.

Trump threatened an economic standoff with South Korea amid increased tensions from North Korea, demonstrating the president’s propensity to fight multiple political battles simultaneously without regard for coordinating a response or fostering cooperation. Glenn Thrush and Mark Landler explain the situation, the president’s criticisms of South Korean President Moon Jae-in and views from observers and analysts at the New York Times.

President Moon’s statement Sunday night tried to play down talk of a dispute between South Korea and the U.S., emphasizing South Korea’s experience of a “fratricidal war” and its commitment to the “denuclearization of the Korean Peninsula” after Trump’s criticisms of Seoul. Anna Fifield explains at the Washington Post.

Japan would increase missile defense capabilities, in cooperation with the U.S., to defend itself against any missile fired by North Korea, Japan’s Prime Minister Shinzo Abe said today, Reuters reports.

If analysis confirms that the bomb was a thermonuclear weapon, it would be a major milestone in North Korea’s weapons program, demonstrating a capability far in advance of that predicted by experts and making the technological development months, or years, before many expected. Joby Warrick observes at the Washington Post.

The U.S. must invest in missile defenses and technology in the face of the North Korea threat because the “the next arena where this is going to play out is in space,” Sen. Ted Cruz (R-Texas) said yesterday, Kelsey Tamborrino reporting at POLITICO.

Swiss President Doris Leuthard offered to mediate the North Korea crisis today, stating that “it’s really time for dialogue,” the AP reports.

The timing of the nuclear test poses a challenge for China and President Xi Jinping, raising tensions and undermining Xi as he welcomes leaders from the B.R.I.C.S. countries (Brazil, Russia, India, China and South Africa) to a summit in southeast China, Jane Perlez explain at the New York Times.

What motivates North Korean leader Kim Jong-un to develop his nuclear arsenal? The oft-cited reason has been to preserve the Pyongyang regime, however some within the Trump administration have questioned the conventional wisdom. Motoko Rich and David E. Sanger explain the various theories at the New York Times.

The U.S. and the world’s response to North Korea “is a shambling mess,” the Trump administration creating confusion, undermining relations with allies, and China and other states failing to effectively rein in Pyongyang. The Washington Post editorial board writes.

What options does China have to deal with North Korea? Tom Phillips sets out some possibilities at the Guardian.

The latest nuclear test seems to have driven a wedge between the U.S. and South Korea, Trump’s criticisms of President Moon and a dispute over trade policy, giving China and North Korea the opportunity to gain a strategic victory. Bryan Harris, Song Jung-a, and Lucy Hornby write at the Financial Times.

U.S. military action against North Korea would put millions of lives at risk in Seoul and the U.S. must be realistic about the threat, or the lack of a threat, posed by Pyongyang. Brad Lennon sets out the views of various experts and analysts at CNN.

The Trump administration should demand that China and Russia accept a “complete embargo” on North Korea, and threaten to impose severe costs on them if they do not comply, Gordon G. Chang writes at The Daily Beast.

What is the difference between a hydrogen bomb and a regular atomic bomb and what impact would this have on the U.S. and its allies? Chris Buckley at the New York Times.

SYRIA

U.S.-backed Syrian forces have captured Raqqa’s Old City, U.S. officials said yesterday, and have taken about 60% of the city – the de facto capital of the Islamic State in Syria. Maria Abi-Habib and Nour Alakraa report at the Wall Street Journal.  

Pro-Syrian government forces made a significant advance on the eastern city of Deir al-Zour yesterday, as part of a multi-pronged offensive to retake the Islamic State-dominated city, demonstrating the changing fortunes for Syrian President Bashar al-Assad and his backers. Reuters reports.

The Lebanese Shi’ite Hezbollah militia group accused the U.S. of putting civilian lives at risk by striking the road ahead of a convoy transporting Islamic State fighters and their families from the Syrian-Lebanese border to eastern Syria near the border with Iraq, Hezbollah said in a statement issued Saturday. Liz Sly reports at the Washington Post.

The convoy transporting the militants and civilian evacuees has split into two groups, the U.S.-led coalition said yesterday, adding that the coalition would continue to monitor the convoy but would not allow it to link up with Islamic State fighters on the Syria-Iraq border. The AP reports.

The fight for Raqqa has seen Kurds and Arabs work together against the Islamic State, but they have different visions for what should happen once the city has been recaptured and the U.S. ceases to support the Kurdish-led Syrian Democratic Forces (S.D.F.). Sarah El Deeb explains at the AP.

IRAQ

Some Islamic State fighters transported from the Syria-Lebanon border to the Iraqi-Syria border may have found their way to Iraq despite the U.S. military’s vow to prevent them from linking up with militants in western Iraq and eastern Syria. Liz Sly and Mustafa Salim report at the Washington Post.

The Islamic State claimed responsibility for a suicide bomb attack on a state-run power station north of Baghdad early on Saturday, killing seven, Reuters reports.

The intensity of the battle against Islamic State has been unrelenting despite the string of U.S.-led coalition victories against the militants in Iraq, Syria and Afghanistan and the Islamic State’s shrinking territory, Helene Cooper explains at the New York Times.

U.S.-RUSSIA DIPLOMATIC RELATIONS

Russia vacated its consulate in San Francisco and two other diplomatic properties in New York and Washington, a senior State Department official said Saturday, complying with an order by the State Department on Thursday that Russia close its three facilities. Thomas Grove reports at the Wall Street Journal.

Russia’s Foreign Ministry protested the decision by U.S. officials to search Russia’s trade mission in Washington upon its closure, summoning a U.S. diplomat in Moscow to explain the decision, according to a statement released Saturday, the Foreign Ministry adding that it feared that the U.S. intelligence service could use the search to “orchestrate an anti-Russian provocation by planting compromising items.” The BBC reports.

A timeline showing the breakdown in U.S.-Russia relations is provided by Amanda Erickson and Julie Vitkovskaya at the Washington Post.

TRUMP-RUSSIA INVESTIGATION

Trump advisers watered down the president’s draft letter firing former F.B.I. director James Comey, according to sources familiar with the situation, a copy of the draft is believed to be with special counsel Robert Mueller. Josh Gerstein and Josh Dawsey report at POLITICO.

The ranking Democrat on the House Intelligence Committee Rep. Adam Schiff (D-Califf.) threatened to subpoena the White House to obtain the draft letter Trump reportedly wanted send to Comey, Schiff said Sunday. Joanna Walters reports at the Guardian.

IRAN

Iran sent two warnings in the last six months to U.S. spy aircraft approaching Iranian airspace, the commander of Iran’s air defense force Brig. Gen. Farzad Esmaili said Saturday, as quoted by the Tasnim news agency. Reuters reports.

An Iranian court upheld the conviction of Chinese-American Xiyue Wang for “collaborating with foreign governments,” making the decision at the same time as Iranian courts upheld sentences for three others facing similar charges, including two U.S.-Iranians and one Lebanese individual, with Washington demanding the immediate release of the U.S. citizens. The BBC reports.

OTHER DEVELOPMENTS

The union representing 19 U.S. diplomats affected by sonic weapons attacks at the embassy in Havana said Friday that some had suffered mild traumatic brain injuries, the State Department spokesperson Heather Nauert stating that an “investigation into the incidents is ongoing,” Felicia Schwartz reporting at the Wall Street Journal.

A small number of women and children have taken up arms against the Philippine army in the fight against Islamic State-linked rebels in the city of Marawi, the military said today, firing on Philippine troops during the final phase of the operation to retake the city. Reuters reports.

President Obama’s letter to President Trump during his inauguration urged Trump to “sustain the international order” and offered further advice, Kevin Liptak reveals the content of the letter at CNN.

The State Department lacks a strategy for Africa, the Trump administration has yet to fill vacancies and is not paying attention to politics and conflict on the continent, James Reinl explains at Al Jazeera.