U.S. Secretary of Defense Ashton Carter has sought to reassure worried lawmakers on the nuclear deal with Iran and stressed that the Islamic Republic and its proxies, including Hizbullah, continue to be a threat.

Iran and its proxies still present security challenges, Carter said on Wednesday at a committee hearing as part of the White House's aggressive campaign to convince Congress to back the Iranian nuclear deal, which calls on Iran to curb its nuclear program in exchange for billions of dollars in sanctions relief.

Jonathan Pollard, the former U.S. Naval intelligence analyst whose conviction of spying for Israel stoked fierce international passions, has been granted parole and will be released from prison in November after nearly 30 years.

The decision to free Pollard from his life sentence, announced Tuesday by his lawyers and then confirmed by the Justice Department, caps an extraordinary espionage case after decades of legal and diplomatic wrangling. Critics have condemned the American as a traitor who betrayed his country for money and disclosed damaging secrets, while supporters have argued that he was punished excessively given that he spied for a U.S. ally.

The White House is in the "final stages" of a plan to close the Guantanamo Bay detention facility, spokesman Josh Earnest said Wednesday.

President Barack Obama made the closure of the controversial offshore prison a priority when he took office in 2009, but the plan has faced numerous setbacks, including Congress blocking the transfer of detainees to U.S. prisons.

The White House launched a new Twitter account Tuesday to defend the Iran nuclear deal, as U.S. lawmakers prepared to debate the long-negotiated agreement.

In its inaugural tweet, @TheIranDeal linked to a resource page about the agreement between Iran and world powers to curb its nuclear program. 

President Barack Obama spoke by phone Wednesday with Vladimir Putin, thanking his Russian counterpart for his role in reaching a deal on Iran's nuclear program.

U.S. ties with Russia have been strained to breaking point over the war in Ukraine, but Russia was an "important" part of the group of nations that negotiated the deal with Tehran.

U.S. President Barack Obama and Saudi Arabia's King Salman on Tuesday discussed the "urgent" need to end fighting in Yemen, hours after Saudi-backed loyalists retook control of Aden airport.

After discussion about a recently inked nuclear deal with Iran, the White House said Obama and Salman "also spoke about the urgency of stopping the fighting in Yemen and the importance of ensuring that assistance can reach Yemenis on all sides of the conflict."

U.S. President Barack Obama and the leader of Vietnam's Communist Party on Tuesday held what both called "candid" discussions on human rights during a historic White House meeting as the onetime enemies seek to bolster ties.

Nguyen Phu Trong is the first general secretary of the Vietnamese Communist Party to visit the United States and the White House, and was given the rare honor of an Oval Office welcome, usually reserved for heads of state and government.

The White House urged Greece and EU leaders Monday to find a compromise to keep the cash-strapped country in the eurozone, after Greeks voted resoundingly to reject an austerity-based bailout.

"The referendum is over, but our view here at the White House remains the same," said spokesman Josh Earnest.

U.S. Senator Bernie Sanders, a self-described democratic socialist and 2016 candidate for president, has applauded Greece's rejection of a bailout referendum at the height of the country's standoff with European Union creditors.

"I applaud the people of Greece for saying 'No' to more austerity for the  poor, the children, the sick and the elderly," Sanders said in a statement late Sunday.

The head of Vietnam's Communist Party will make a first-ever visit to the White House next week, meeting President Barack Obama on the 40th anniversary of the end of the war between the two nations.

The landmark trip underscores strengthening ties between the former wartime enemies amid regional maritime tensions involving China.