On U.S. Secretary of State John Kerry's Swiss bike rides last week to unwind from intense Iran nuclear talks, one emerging tricky issue may well have been going round his head: U.N. sanctions.

According to negotiators involved and experts, this has become a major snag as Iran and six major powers push for the outlines of a landmark deal by March 31 in marathon talks resuming in a few days.

North Korea's military on Sunday threatened to blow up balloons that South Korean activists plan to send over the heavily-militarized border carrying 10,000 DVDs of the satirical Hollywood film "The Interview".

Activists plan to launch copies of the film -- a comedy about a fictional CIA plot to assassinate North Korean leader Kim Jong-Un -- as well as 500,000 propaganda leaflets across the border on or around March 26.

The United States said it had evacuated all its staff from Yemen, whose embattled president has appealed for "urgent intervention" by the U.N. Security Council as attacks by Iran-backed rebels bring his country nearer to civil war.

"Due to the deteriorating security situation in Yemen, the U.S. government has temporarily relocated its remaining personnel out of Yemen," State Department spokesman Jeff Rathke said in a statement.

Turkish prosecutors on Friday demanded life terms for 28 suspects accused of setting up bugs to eavesdrop on President Recep Tayyip Erdogan and other top officials.

The case is one of the key pillars in Erdogan's offensive against followers of U.S.-based preacher Fethullah Gulen, who he accuses of setting up a parallel state aimed at ousting him from power. 

Nigeria's President Goodluck Jonathan on Friday said the military hopes to recapture towns seized by Boko Haram within a month, in what would be a swift victory after six years of bloody conflict.

But experts warned against any premature declaration of victory, with the militants still proving capable of carrying out deadly hit-and-run strikes and indications of coalition lapses.

A top Yemeni officer linked to the Shiite militia opposed to President Abedrabbo Mansour Hadi escaped an assassination bid near the southern city of Aden, a security official said Friday.

Four people were killed in an ambush on the Lahj-Taiz road but General Abdel Hafedh al-Sakkaf, the special forces chief in Aden, escaped unharmed, said the official from Lahj.

Marathon talks towards an Iran nuclear deal looked likely Friday to go down to the wire of a March 31 deadline, with negotiations in Switzerland set to break up and resume next week.

U.S. Secretary of State John Kerry was set to leave Lausanne Saturday after almost a week of negotiations which "resume next week", State Department spokeswoman Marie Harf said.

Shinzo Abe is expected to become the first Japanese prime minister in history to address a joint session of the U.S. Congress, crowning an April visit focused on deepening trade and military ties.

Abe hopes to make the speech during a trip to the United States at the end of next month, around Japan's "Golden Week" holiday, diplomatic and legislative sources told AFP.

For much of the past two decades the U.S. military has been waging war in Iraq. And one U.S. Army officer has been there for just about every painstaking step of it.

General Martin Dempsey has experienced first hand America's tortuous history in Iraq, from the 1991 Gulf War's swift victory to the troubled occupation after the 2003 U.S. invasion.

A U.S. Senate committee will vote April 14 on a bipartisan measure requiring President Barack Obama to submit any international nuclear deal with Iran for congressional review, the legislation's authors said Thursday.

Senate Foreign Relations Committee chairman Bob Corker and top panel Democrat Robert Menendez agreed to push back a vote on the controversial bill until two weeks beyond the March 31 deadline negotiators set for the outlines of an accord between Iran and world powers aimed at preventing the Islamic republic from developing nuclear weapons.