President Barack Obama has defended the use of drones in a "just war" of self-defence against deadly militants and a campaign that had made America safer.

In a wide-ranging speech on a programme shrouded in secrecy, he said there must be "near certainty" that no civilians would die in such strikes. In a renewed push to shut Guantanamo Bay, he said he had lifted a moratorium on prisoner transfers to Yemen. Mr Obama also defended the use of drones to kill four US citizens. He said, we are at war with an organisation that right now would kill as many Americans as they could if we did not stop them first, he said this is a just war a war waged proportionally, in last resort, and in self-defence."

A North Korean envoy visiting China says Pyongyang is ready to open up dialogue with all the relevant parties.

Vice Marshal Choe Ryong-hae flew to China as North Korean leader Kim Jong-un's special envoy. China is North Korea's biggest trading partner and closest ally. But relations between the neighbors had cooled after China supported tightened UN sanctions following Pyongyang's third nuclear test. Mr Choe met senior Chinese official Liu Yunshan, a member of the Standing Committee of China's Political Bureau. He is the most senior North Korean official to visit China since August 2012 and his visit follows weeks of tension on the Korean peninsula and a series of threats from the North. Mr Liu said that all relevant parties should support the goal of de-nuclearisation, and called for a return to six-party talks, Chinese media said. Mr Choe said North Korea appreciated China's efforts to maintain peace and stability, and was "willing to accept the suggestion of the Chinese side and launch dialogue with all relevant parties", China's state-run news agency Xinhua reported.

Five people were killed and more than 50 wounded in overnight clashes in Tripoli between Lebanese gunmen backing rival factions in Syria's civil war.

Tripoli has suffered sporadic sectarian violence since the Sunni Muslim-led uprising against Syrian President Bashar al-Assad broke out in March 2011. The use of heavy weapons stopped at sunrise and only the sound of sniper fire could be heard. The militant groups tend to fight through the night and rest by day. The two groups have clashed in Tripoli on and off for decades, but the Syrian conflict has reopened old wounds, with each side accusing the other of using the city as a base for sending fighters and weapons in and out of Syria.

World powers have urged Syrian President Bashar al-Assad to commit to peace, but warned that if he fails to negotiate a political transition they would boost their backing of the opposition.

The stark warning came from a meeting of the friends of Syria group, which held talks on in Amman to try to agree the contours of a peace conference to end the war.The conflict, now in its third year, has claimed some 94,000 lives. The United States and Russia have backed opposite sides in the conflict, but hope to bring the warring sides together at the conference next month, although a date and venue remain unclear. Addressing a joint press conference with his Jordanian counterpart Nasser Judeh ahead of a meeting of the friends of Syria group in Amman, John Kerry said we will call on President Assad to make the same commitment to find peace in his country. He said a US-Russian proposed peace conference in Geneva seeks to end the bloodshed what has cost tens of thousands of lives. After meeting late into the night, the 11 ministers from the friends of Syria group laid out a grim choice for Assad, if the regime refused to negotiate a transitional government, then they would boost their support for the opposition. A final statement said, "the ministers also emphasized that until such time as the Geneva meeting produces a transitional government, they will further increase their support for the opposition and take all other steps as necessary.

In United States, a Florida man was shot and killed while being questioned by Boston bombing investigators after he lunged at them with a knife.

Officials have said the shooting took place in Orlando as officials questioned Ibragim Todashev, 27. The FBI initially said their agent had killed Todashev, but an updated statement left it unclear who had fired the fatal shot. The FBI said two Massachusetts state police officers were also in the room.