U.S. President Barack Obama marked the tenth anniversary of the Iraq invasion on Tuesday by paying tribute to the "sacrifice" of U.S. troops, but had few words for the Iraqi people.

In a muted statement, issued on the eve of a visit to a Middle East much changed since his predecessor George W. Bush unleashed the 2003 war, Obama promised to support wounded American veterans of the conflict.

Afghanistan's presidential spokesman on Tuesday described the NATO-led military operation in the country as "aimless and unwise", in the latest government broadside against the coalition.

Aimal Faizi, spokesman for President Hamid Karzai, hit out after NATO chief Anders Fogh Rasmussen rejected Karzai's recent allegations that it was working in collusion with Taliban militants.

World powers gave Iran fresh details on a proposed deal aimed at ending international concern over Tehran's nuclear program during talks in Istanbul, the European Union said Tuesday.

At the talks on Monday, experts from the five permanent U.N. Security Council members -- Britain, China, France, Russia and the U.S. -- plus Germany "had technical discussions with Iran," said a brief statement from a spokesman for EU foreign policy chief Catherine Ashton.

Baghdad is "looking the other way" as Iran sends military equipment through Iraqi airspace to Syrian President Bashar Assad's regime amid the ongoing conflict in Syria, a U.S. official said.

The official, who spoke on condition of anonymity, called on Iraq to randomly search Iranian planes flying to Syria, and said Washington had complained to "all levels of the Iraqi government" about the lack of inspection.

North Korea has produced another video showing the United States under attack, this time with the White House and the U.S. Capitol literally in the crosshairs.

The four-minute video titled "Firestorms will rain on the Headquarters of War" (http://y2u.be/DyapeCiOl9A) was posted Monday on the YouTube channel of the North's official website, Uriminzokkiri, which distributes news and propaganda from the state media.

Beijing and Washington have "enormous shared interests,” China's new President Xi Jinping told the U.S. Treasury chief on Tuesday in his first major diplomatic encounter since taking office.

"In the China-U.S. relationship, we have enormous shared interests, but of course, unavoidably, we have some differences," Xi said to Treasury Secretary Jacob Lew at the Great Hall of the People in Beijing.

U.S. President Barack Obama urged Iran on Monday to take "immediate and meaningful steps" to move "toward an enduring, long-term settlement" with the world over its disputed nuclear program.

In a White House statement, Obama added that if Iran took such action "the Iranian people will begin to see the benefits of greater trade and ties with other nations, including the United States."

The United States is struggling to track a fragmented Syrian opposition and has found it increasingly difficult to get a clear picture of rebel factions, the U.S. military's top officer said Monday.

"About six months ago we had a very opaque understanding of the opposition and now I would say it's even more opaque," General Martin Dempsey, chairman of the Joint Chiefs of Staff, told the Center For Strategic and International Studies (CSIS), a Washington-based think tank.

U.S. State Department spokeswoman Victoria Nuland condemned on Monday the Syrian bombing of Lebanese border regions, stating that “this step violates the country's sovereignty and is absolutely unacceptable”.

“Syrian warplanes Monday bombed northern Lebanon for the first time,” Nuland confirmed to reporters, denouncing the move as "a significant escalation" of the conflict.

The United States will not oppose moves by some European nations to arm Syrian rebels battling President Bashar Assad, top U.S. diplomat John Kerry said Monday.

"President (Barack) Obama has made it clear that the United States does not stand in the way of other countries that have made a decision to provide arms, whether it's France or Britain or others," Kerry told reporters.