The White House on Monday flatly rejected claims that Pakistan was told in advance about a 2011 special operations raid that killed al-Qaida leader Osama bin Laden. 

Veteran U.S. journalist Seymour Hersh claimed in a British publication that Pakistan's security services not only knew about the raid, but had been holding bin Laden prisoner since 2006.

A U.S. government panel on Thursday approved measures to boost security at the White House, adding a new set of metal spikes to the fence after a series of breaches.

The National Capital Planning Commission approved the temporary addition of roughly seven-inch (18-centimeter) "pencil point" spikes, spokesman Stephen Staudigl said.

Democratic presidential frontrunner Hillary Clinton called Tuesday for a path to citizenship for some of the 11 million illegal immigrants in the United States, drawing a sharp contrast with her Republican foes.

The former secretary of state and ex-first lady called immigration a family and economic issue, and pressed for expanding a program to help not just immigrant children but their parents as well stay in the U.S.

President Barack Obama is expected to weigh in on ongoing tensions in America over police treatment of blacks -- and possibly offer a glimpse of his post-White House plans -- during remarks in New York on Monday.

Obama will travel to the Bronx to spin off the "My Brother's Keeper" initiative as an independent non-profit organization dedicated to improving opportunities for young black men.

Former U.S. president Bill Clinton said in an interview that aired Monday he will keep giving lucrative speeches "to pay our bills" while wife Hillary Clinton runs for the White House.

Defending his charity work on a trip to Africa, Clinton said Hillary told him no foreign official has sought to influence her through donations to the family's foundation, which has come under fire for accepting millions of dollars from foreign governments.

Former Hewlett Packard chief executive Carly Fiorina announced Monday she is running for the 2016 Republican nomination, in a statement posted on Twitter.

"I am running for president," wrote Fiorina, 60, the only woman so far to join the crowded Republican presidential field.

U.S. Senator Bernie Sanders launched his populist, liberal campaign for the White House on Thursday, savaging an American economic system that creates "immoral" and unsustainable disparities between rich and poor.

"We're in this race to win," the 73-year-old Sanders, an independent lawmaker who is little known outside political circles and his home state of Vermont, told reporters at a low-key, rushed announcement on the lawn outside the U.S. Capitol, where he has served in Congress since 1991.

U.S. President Barack Obama on Thursday described the World War I massacre of Armenians as "terrible carnage", but avoided the term genocide, as tempers flared ahead of the 100th anniversary of the bloodshed.

Friday marks a century since the start of the massacres waged by Ottoman forces, which Armenia says killed 1.5 million people between 1915 and 1917. 

Hackers who penetrated the State Department and White House computer networks in recent months were "Russian speakers," security researchers said Wednesday.

The hackers have aimed at high-profile targets including U.S. government and commercial networks as well as in Germany, South Korea and Uzbekistan, according to researchers at Kaspersky Lab, a Russian-headquartered security firm.

U.S. Secret Service agents arrested an intruder who scaled the White House fence late Sunday, officials said.

The individual was immediately arrested while climbing the fence on the south side of the presidential mansion, Secret Service spokesman Brian Leary said in a statement.