The failed coup attempt in Turkey and President Recep Tayyip Erdogan's firm crackdown on the alleged plotters have aggravated ties between Washington and Ankara, already poisoned by the war in Syria and human rights issues.

Although they are NATO allies and officially partners in the fight against the Islamic State group, the United States and Turkey have seen their relations take an icy turn in recent months.

Turkish Prime Minister Binali Yildirim on Tuesday said his government had dispatched dossiers to the United States for the extradition of US-based preacher Fethullah Gulen over his alleged links to Friday's attempted coup.

The White House sharply criticized Monday renewed heavy fighting in South Sudan's capital city Juba that has pushed thousands of people to flee.

"The United States condemns in the strongest terms the return to violence in South Sudan. It must stop," National Security Advisor Susan Rice said in a statement.

The United States demanded an immediate end to renewed fighting in the capital of South Sudan on Sunday, ordering all non-essential personnel out of the troubled country.

"The United States strongly condemns the latest outbreak of fighting in Juba today between forces aligned with President Salva Kiir Mayardit and those aligned with First Vice President Riek Machar Teny, including reports we have that civilian sites may have been attacked," State Department spokesman John Kirby said in a statement.

The United States on Tuesday criticized Israel's plans to build 560 new settler homes in the West Bank, warning that they would be part of "systematic" land seizures undermining chances for peace.

Israel's green light for the homes came days after a key report from the diplomatic Quartet -- the United States, European Union, United Nations and Russia -- warned that Israel's settlement expansion and confiscation of Palestinian land were eroding the possibility of a two-state peace settlement.

The Pentagon on Friday rejected a Russian proposal to launch joint air strikes against jihadists from next week in Syria, where they have been conducting separate bombing campaigns.

"We do not collaborate or coordinate with the Russians on any operations in Syria," Pentagon spokesman Navy Captain Jeff Davis told reporters, explaining that Washington and Moscow have separate military objectives.

NATO said Wednesday its special forces are supporting Afghan troops in Kunduz after Taliban insurgents seized the city, fought off a counter-attack and advanced on the airport to shore up their biggest victory in 14 years.

Heavy fighting was underway near the northern city's airport where government forces retreated, highlighting the potent challenge the militants pose after their lightning capture of Kunduz.

Pope Francis arrived in Philadelphia Saturday for the final leg of his triumphal tour of the United States, with hundreds of thousands expected to turn out for his weekend visit focused on families.

The head of the world's 1.2 billion Catholics landed in the City of Brotherly Love after a short flight from New York, where he spent a whirlwind 36 hours that included an emotional visit to Ground Zero and mass at Madison Square Garden.

NATO head Jens Stoltenberg told Agence France Presse Thursday he was concerned by Russia's "substantial" military build-up in Syria and urged Moscow to play a constructive role in the fight against Islamic State jihadis.

"It underlines the importance of Russia making clear what are their intentions," Stoltenberg told Agence France Presse in an interview at NATO HQ in Brussels.

The death toll from monster wildfires raging in northern California has risen to five with the discovery of two new victims, authorities said on Thursday.

Both were killed in the so-called Valley fire, one of two giant blazes that have destroyed hundreds of homes and displaced thousands in the drought-stricken state.