Barack Obama insisted Monday he had faith in the Afghan war mission after former Pentagon chief Robert Gates charged the president lacked passion for military action and soured on his own troop surge.

In his first public comments on criticisms of his role as commander-in-chief in new memoirs by Gates, Obama said he had a duty to constantly question U.S. military tactics and "sweat the details" when sending young men and women to war.

The U.S. Supreme Court appeared to be preparing Monday to limit the president's power to appoint high-level judges and officials while Congress is in recess.

By law, the president has the right to choose the nominees and lawmakers have the right to offer "advice and consent."

U.S. President Barack Obama on Monday urged Congress to give diplomacy a chance in resolving the Iranian nuclear issue, with some American lawmakers urging fresh sanctions on Tehran.

Obama made the remarks following a meeting with Spanish Prime Minister Mariano Rajoy in the Oval Office.

U.S. President Barack Obama will travel to Toluca, Mexico on February 19 for a North American leaders summit, the White House said Monday.

The meeting will be hosted by Mexico's President Enrique Pena Nieto and will also include Canadian Prime Minister Stephen Harper.

Former U.S. defense secretary Robert Gates insisted Monday his new memoir is "even-handed" and accused opponents of President Barack Obama of misrepresenting it to score political points.

Gates' book has been widely portrayed as an attack on Obama's war leadership, but the author himself said he had in fact agreed with the major decisions the US president made on Afghanistan.

World leaders paid tribute Saturday to former Israeli prime minister Ariel Sharon, calling him a patriot who made "brave decisions" to secure his country's future, but his foes derided him as a "criminal".

U.N. Secretary General Ban Ki-moon hailed Sharon on Saturday as a "hero" to Israelis, who would leave behind a "legacy of pragmatism" in the Middle East.

U.S. President Barack Obama will unveil reforms to the country's spying activities on January 17, his spokesman said Friday, following a review of the National Security Agency (NSA).

White House spokesman Jay Carney said that Obama's remarks next Friday would show the "outcomes of the work that has been done on the review process."

The top U.S. negotiator in talks to secure a long-term security deal with Afghanistan has warned that President Hamid Karzai is unlikely to sign the agreement on time, The Washington Post reported Thursday.

The assessment was made in recent days by U.S. Ambassador James Cunningham in a classified cable, after President Barack Obama's administration repeatedly extended the deadline for the agreement, originally due to be signed early last fall.

The White House on Wednesday fought back against former Pentagon chief Robert Gates' blunt criticism of President Barack Obama's war leadership and damning of Vice President Joe Biden.

Gates, who served six presidents in senior national security jobs, sent political shockwaves through Washington with his unsparing assessments of the administration in his new book.

U.S. President Barack Obama met top spy chiefs Wednesday as he finalized a decision on how to rein in National Security Agency spying sweeps following revelations by Edward Snowden.

Obama met the heads of the NSA, CIA, FBI and the director of national intelligence as part of a string of meetings with advocates on both sides of the debate on balancing privacy and national security.