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.

YEMEN

A Saudi-led coalition airstrike killed 25 people and wounded close to 400 yesterday when it targeted a Scud missile base in Houthi-controlled capital, Sana’a. [Reuters]  Civilians have given “vivid accounts” of the blast on social media. [New York Times’ Robert Mackey]

The U.S. has positioned two further warships in the Arabian Sea, citing the current instability in Yemen. [Central Command]  The addition of the aircraft carrier Theodore Roosevelt and a guided missile cruiser brings the number of American warships in the waters off Yemen to 12, a “warning to Iran” over its shipments of weapons to Houthi rebels, report Michael D. Shear and Matthew Rosenberg. [New York Times]

Iran’s deputy foreign minister expressed optimism that a ceasefire would be announced later today, according to the Iranian Tasnim news agency. [Reuters]

Without Houthi withdrawal there will be no immediate ceasefire in Yemen, Gulf envoys told UN Secretary General Ban Ki-moon yesterday. [Al Arabiya News]

Houthi rebels are confident that their familiarity with mountain warfare would guarantee success against their Arab adversaries, the Saudi-led air campaign making “little headway” since it began on March 26. [Reuters]

The Saudi role in Yemen’s war has “sparked a patriotic fervor” in the kingdom, despite opinion outside the country being much more divided on the merits of the campaign. [NPR’s Leila Fadel]

IRAQ and SYRIA

Syrian President Bashar al-Assad has denied the presence of Iranian troops in Syria, during an interview on French television. Assad added that his intelligence forces were in contact with their French counterparts, but denied any “cooperation or exchange of information.” [France 24]

The UN Security Council has demanded unobstructed humanitarian access to Yarmouk Palestinian refugee camp in Damascus, calling on all parties to the conflict to support the UN framework for responding to the humanitarian situation in the camp. [Reuters’ Louis Charbonneau]

Moderate Syrian opposition fighters are set to begin training in Turkey next month, despite disagreement between the Obama administration and Ankara over what enemy they will fight upon return to Syria. [Washington Post’s Karen DeYoung] 

The Islamic State carried out two separate mass killings in Iraq this week, according to local sources, leaving at least 35 people dead. [Al Jazeera]

U.S.-led airstrikes continue. Coalition military forces carried out 10 airstrikes against Islamic State targets in Syria between 8am April 19 and 8am April 20. Separately, military forces conducted 26 strikes on targets in Iraq. [Central Command]

A British couple has been arrested in Turkey with their four children, suspected of being on route to Syria to join an Islamist group. [The Guardian’s Caroline Davies]

The proliferation of the Islamic State has led to “repercussions on the Salafi jihadist scene” in Jordan, highlighted by a recent “evolution” in the group’s internal dynamics, writes Mona Alami. [Al Monitor]

AFGHANISTAN

A bomb explosion in Afghanistan’s Kandahar province has killed three people and wounded another 17 today. No group has immediately claimed responsibility for the attack in Kandahar, the heartland of the Taliban. [AP]

NPR “On the Road.” This week, Rebecca Hersher will explore the current security situation in Afghanistan, including how well equipped the Afghan security forces are to tackle the Taliban, and what a non-combat mission looks like for the remaining U.S. troops in the country.

IRAN NUCLEAR DEAL

The crisis in Yemen is a “surprise complication” for the nuclear diplomacy, with both the U.S. and Iran sending warships to the region in support of opposing forces, reports Michael Crowley. [Politico]

The key to an acceptable nuclear deal is “not the rollback of [Tehran’s nuclear] program, but our ability to monitor it,” explains Ambassador Dennis Ross. [Politico]

RUSSIA and UKRAINE

The U.S. has begun military training exercises in western Ukraine, with President Petro Poroshenko welcoming the arrival of American troops as a “new stage of cooperation” between the two countries. [DoD News; Wall Street Journal’s Alan Cullison]

The leader of an Islamist militant group in the North Caucasus was killed in a counterterrorism operation on Sunday, Russian authorities have confirmed. [Reuters’ Gabriela Baczynska]

Russia and the U.S. should jointly decide to remove the “launch-on-warning” tactic from their nuclear strategies, write former vice chairman of the Joint Chiefs of Staff James E. Cartwright and retired major general Vladimir Dvorkin, commenting on how to avoid a nuclear war. [New York Times]

OTHER DEVELOPMENTS

A bomb exploded outside the Spanish embassy in Tripoli, Libya, yesterday, the latest in a series of assaults on foreigners and embassies in the country. [Reuters]

Ousted President Mohamed Morsi has been sentenced to 20 years in prison by an Egyptian court in relation to the detention and use of force against protesters during his presidency. [NBC News’ Charlene Gubash]

A group of NGOs has written a letter to members of the EU Genocide Network, calling on them to take on a role in bringing to account those involved in the CIA detention and interrogation program, as detailed in the Senate Select Committee report published last December.

Loretta Lynch has slim Republican support, but it will be enough to secure her long-delayed confirmation as attorney general, with a vote potentially this week. [The Hill’s Tim Devaney]

Iran has charged Washington Post reporter Jason Rezaian with four serious crimes, including espionage, nine months after his arrest and detention. The charges have been criticized as “absurd” by the White House, which called for his immediate release. [Washington Post’s Carol Morello]

The current U.S.-Israel friction differs from previous “bad patches,” with the main issue now being how the U.S. views itself, according to Bret Stephens. [Wall Street Journal]

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