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 TEST

North Korea claims it has successfully conducted its first underground hydrogen bomb test, a weapon more powerful than an atomic bomb. If the claims are authenticated, it would mark a significant advancement in its nuclear capabilities and the fourth nuclear test since 2006. [BBC]  The Wall Street Journal provides a transcript of the statement by North Korea announcing the test.

The Guardian has live updates as the story develops.

Russia says that it does not yet have confirmation that North Korea conducted the test, calling for restraint to avoid the “uncontrolled growth of tensions” in Northeast Asia. [AP]

US officials “cannot confirm these claims at this time,” according to spokesman for the White House National Security Council, Ned Price. [New York Times’ David E. Sanger and Choe Sang-Hun]

The US Geological Survey recorded a magnitude 5.1 earthquake close to North Korea’s nuclear test site in the northeast of the country. [Wall Street Journal’s Alastair Gale and Kwanwoo Jun]

A number of experts have said that the evidence initially suggests that the test was of an explosive involving uranium or plutonium rather than a much more powerful hydrogen bomb, as claimed by Pyongyang. [The Guardian’s Justin McCurry and Michael Safi]

The test is said to be a “grave threat to international peace and security,” according to the head of the Comprehensive Nuclear-Test-Ban Treaty Organisation. [The Guardian’s Justin McCurry and Tom Phillips]

IRAN-SAUDI ARABIA DISPUTE

Iran’s President Hassan Rouhani said Saudi Arabia “cannot hide its crime” of executing Shi’ite cleric, Nimr al-Nimr by severing diplomatic ties with Tehran. Iran has distanced itself from the attack on the Saudi Embassy in Tehran which led Riyadh to cut ties. [Reuters’ Bozorgmehr Sharafedin]

Iraq will mediate the dispute between the Saudis and the Iranians, the country’s foreign minister, Ibrahim al-Jaafari said today. [Reuters]

Gulf States are protecting their interests in the Iran-Saudi Arabia dispute, with the smaller Sunni Gulf nations adopting a more measured approach than Kuwait, the UAE and Bahrain. [New York Times’ Declan Walsh]

ISIS has threatened to destroy Saudi prisons holding jihadists following Riyadh’s execution of 47 people, including 43 convicted al-Qaeda militants. [Reuters]  Saudi officials have said that the executions were intended to send a strong message to dissenters and would-be militants in the kingdom. [New York Times’ Kareem Fahim]

The Wall Street Journal editorial board argues that a “Middle East dividing into Sunni and Shi’ite blocs is the predictable consequence of Mr Obama’s strategy of retreat from the region.”

The New York Times editorial board observes that “it is hard to imagine that the Sunni rulers of the kingdom were not aware of the sectarian passions the killings would unleash around the region,” concluding that “there is no reason for the Obama administration to do anything less than clearly condemn this foolhardy and dangerous course” being taken by the kingdom.

IRAQ and SYRIA

The dispute between Iran and Saudi Arabia threatens to undermine the Iraqi governments’ efforts to combat the Islamic State, potentially “foil[ing] Sunni-Shi’ite cooperation,” and benefitting ISIS, report Ben Hubbard et al. [New York Times]  Saudi Arabia’s execution of Nimr al-Nimr angered many in Iraq’s Shi’ite majority. [Wall Street Journal’s Matt Bradley and Ghassan Adnan]

The Islamic State has launched a major offensive against the key Iraqi city of Haditha, with hundreds killed in the first days of fighting, according to a local source. [Al Jazeera]  The offensive follows the militant group’s defeat in Ramadi last month. [Washington Post’s Erin Cunningham]

US-led airstrikes continue. The US and coalition military forces carried out one strike against Islamic State targets in Syria on Jan. 4. Separately, coalition forces conducted a further 19 strikes on targets in Iraq. [Central Command]

A profile of London man Siddhartha Dhar, the key suspect in efforts to identify a British-accented militant featured in ISIS’s latest propaganda video, from Alexis Flynn and Jenny Gross at the Wall Street Journal.  And VICE News has an interview with Dhar from 2013.

“The secret, hypocritical gay world of ISIS,” from Tim Teeman at The Daily Beast.

AFGHANISTAN

A US soldier was killed and two others injured yesterday in fighting in Afghanistan’s restive Helmand province, Pentagon Press Secretary Peter cook said.

The death took place in Marja, an area where American Special Operations forces have been trying to assist local Afghan forces push back against a Taliban offensive. Rod Nordland provides details surrounding the death. [New York Times]

The Pentagon did not comment on why the American troops were stationed in the area or what their mission was, observes Nancy A. Youssef, suggesting that it’s “all part of an increasingly dangerous Afghan war that’s being fought more and more in the shadows.” [The Daily Beast]

YEMEN

The Saudi-led coalition reportedly fired missiles yesterday at a center for the blind in the country’s capital, Sana’a. Ryan Devereaux provides the details. [The Intercept]

The civilian death toll in Yemen’s civil war has reached close to 2,800, according to new UN figures. The number of civilian casualties sharply increased in December despite a ceasefire. [UN News Centre; New York Times’ Nick Cumming-Bruce]

OTHER DEVELOPMENTS

The FBI cannot place the San Bernardino shooters for 18min of December’s attack which left 14 dead and has appealed to the public for assistance. [USA Today’s Kevin Johnson]

Russian hackers are suspected of involvement in a cyberattack on the Ukrainian power grid in December, sources told The Daily Beast’s Shane Harris.

An Iraqi Kurdish journalist working with VICE News has been released on bail; Mohammed Ismael Rasool was held for more than four months on terrorism charges in a maximum security prison after he was detained with two VICE News colleagues in August.

Jordan has released the deputy leader of the Muslim Brotherhood in the country; Zaki Bani Rushaid served a 13 month sentence for criticizing the UAE. [New York Times’ Rana F. Sweis]

The UN is investigating fresh allegations of sexual abuse by peacekeepers in Central African Republic. [UN News Centre]  These latest allegations follow a series of sexual abuse accusations lodged against blue helmets in 2015. [Al Jazeera]

“These days, we all live at risk of random terror,” writes David Brooks, considering the “age of small terror,” at the New York Times.

The Wall Street Journal editorial board comments on new US visa waiver restrictions passed by Congress in December and the impact on relations with Iran, arguing that its “time for choosing whether Iran or Congress poses the greater danger to the US.”