The United States welcomed Tuesday former Cuban leader Fidel Castro's belated response to the thaw in ties between the Cold War foes as a sign that change is underway in Havana.

"We take his reference of 'international norms and principles' as a positive sign," State Department spokeswoman Jen Psaki told reporters, after Castro's letter was released.

The pilot of a unmanned commercial drone that crashed at the White House and sparked a security alert works for the U.S. National Geospatial-Intelligence Agency, officials revealed Tuesday.

The agency -- which provides vital imagery and analysis for U.S. military and civilian intelligence agencies -- said one of its staff members had been questioned by the Secret Service.

U.S. President Barack Obama won breathing room Tuesday for his nuclear dialogue with Iran, as legislation calling for strict new sanctions against the Islamic republic lost some crucial support in Congress.

Senator Robert Menendez announced that he and several fellow Democrats had assured Obama they would not vote in support of new sanctions prior to March 24, shortly before a negotiations target date.

U.S. President Barack Obama led a heavyweight delegation to Saudi Arabia on Tuesday to meet new King Salman and shore up ties that have suffered in recent years.

The longstanding allies remain bound by shared interests in regional stability and oil.

President Barack Obama said the United States could be India's "best partner" Tuesday as he wrapped up a three-day visit to New Delhi by highlighting the shared values of the world's biggest democracies.

Speaking to an audience of young people, the U.S. president reiterated that the relationship between Washington and New Delhi "can be one of the defining partnerships of this century" but warned the battle against climate change would be doomed unless India was fully on board.

U.S. President Barack Obama and the new Saudi king are expected to discuss the military campaign against Islamic State group extremists and the crisis in Yemen at upcoming talks in Riyadh, the White House said Monday.

Obama's brief visit to the Saudi capital on Tuesday was mainly intended as an opportunity to meet King Salman "and to pay respects to the family and to the people of Saudi Arabia" after the death last week of long-time ruler King Abdullah, a senior official said.

Rain failed to dampen spirits at India's Republic Day parade Monday as Barack Obama became the first U.S. president to attend the spectacular military and cultural display in a sign of the nations' growing closeness.

Thousands of cheering spectators braved wet weather and heavy security to watch the parade, which marks the birth of modern India and includes everything from tanks and state-of-the-art weaponry to camels and traditional dancers.

Narendra Modi has trumpeted a new era of friendship with Barack Obama but experts say the Indian premier will be careful not to alienate traditional ally Russia or giant rival China.

The U.S. president was the chief guest at India's Republic Day parade on Monday after accepting an invitation that is one of the biggest honors a country can bestow on a foreign leader.

New Saudi King Salman is expected to use President Barack Obama's stopover on Tuesday to push for greater U.S. involvement in resolving Middle East crises, analysts say.

Obama, accompanied by his wife Michelle, is cutting short a visit to India to convey his condolences after the death of ailing King Abdullah last Friday.

U.S. President Barack Obama and India's Prime Minister Narendra Modi broke the deadlock on a long-stalled nuclear pact Sunday as they hailed a new era of friendship between the world's two largest democracies.

After greeting Obama with a bear hug as he stepped off Air Force One, Modi then trumpeted the "chemistry" with his fellow leader on the first of a three-day visit to the Indian capital.