U.S. President Barack Obama insisted Tuesday that his disagreement with Israel's Prime Minister Benjamin Netanyahu represents a substantial policy difference and not a personal vendetta.

As the Israeli premier works to build a new coalition government at home, he faces one of the worst confrontations in his stormy relationship with the White House.

Israel has spied on Iran's nuclear talks with the United States and other major powers, the Wall Street Journal reported Tuesday.

Israel quickly dismissed the report as "not true", and denied spying on the United States.

President Barack Obama is to meet Tuesday with his Afghan counterpart Ashraf Ghani, who has asked Washington for "flexibility" on the pace of U.S. troop withdrawal from the war-torn country after a presence of more than a decade.

With the end of the U.S. combat mission in 2014, Afghan forces have taken over responsibility for security across the conflict-scarred nation, still wracked by a militant insurgency.

The White House on Monday said a controversial program exposed by whistleblower Edward Snowden that covertly collects masses of telephone data will end if Congress does not expressly reauthorize it.

The program -- which secretly tracks when telephone calls are made, to whom and for how long -- was introduced after the September 11, 2001 attacks on the World Trade Center and Pentagon.

U.S. President Barack Obama hosted his would-be presidential successor Hillary Clinton at the White House on Monday, in a previously unannounced meeting.

"President Obama and Secretary Clinton enjoy catching-up in person when their schedules permit," White House press secretary Josh Earnest said.

American lawmakers voted overwhelmingly Monday to urge President Barack Obama to provide Ukraine with lethal weapons to defend itself against Russian "aggression."

The U.S. House of Representatives approved the resolution in a broadly bipartisan 348-48 vote, heaping further pressure on the Obama administration to end its delays in providing weapons and other heavy military equipment to Kiev forces.

U.S. President Barack Obama on Thursday called his Tunisian counterpart Beji Caid Essebsi to offer condolences for the deadly museum attack and continued assistance in the investigation.

Obama "extended sympathy, on behalf of all Americans, to the victims' families and loved ones," the White House said, following the attack on the Bardo Museum in Tunis which killed 21 people.

U.S. prosecutors said Wednesday they will not pursue criminal charges against an intelligence agency employee who lost control of a hobby drone that crashed into the White House gardens, sparking a Secret Service investigation.

The man, whose name was not released, had been flying a friend's DJI Phantom "quadcopter" around his downtown Washington apartment late on January 25 and early the next morning. 

The U.S. Secret Service has requested $8 million to build a replica of the White House for use in training agents to prevent incidents like last year's mansion intrusion, the agency's director said Tuesday.

Joseph Clancy said the agency's current rudimentary training facility, in Beltsville, Maryland, is not to scale, and has "no structures, vehicle gates, lighting, or other aides to enhance the training simulations."

The White House has confirmed that any nuclear agreement between Iran and the P5+1 group of world powers would be subject to a vote by the U.N. Security Council.

The acknowledgement by President Barack Obama's chief of staff Denis McDonough comes as the White House butts heads with Republicans over whether the U.S. Congress should vote on any deal.