At least four people were killed and five more hurt Thursday when a small plane crashed into an airport training building housing flight simulators in the U.S. state of Kansas.

The twin-engine aircraft lost engine power shortly after takeoff and crashed while attempting to return to the runway at the Wichita Mid-Continent Airport, the Federal Aviation Administration said.

The U.S. military will launch new medical examinations for troops and veterans exposed to chemical weapons in Iraq, and review claims they were ordered to stay silent about such contact, officials said Thursday.

Defense Secretary Chuck Hagel has asked the U.S. Army and Navy secretaries to ensure troops affected by chemical munitions "are receiving the care and the support they require," spokesman Rear Admiral John Kirby said.

Pentagon chief Chuck Hagel has castigated the U.S. strategy in Syria in a memo to the White House, saying Washington must explain its intentions toward President Bashar al-Assad's regime.

The memo was sent last week to President Barack Obama's national security adviser, Susan Rice, a defense official said Thursday, confirming a New York Times report.

The Norwegian government said Thursday it would send about 120 troops to Iraq to help train its armed forces in the fight against the Islamic State jihadists.

Prime Minister Erna Solberg however stressed that "the Norwegian military will not follow the Iraqi soldiers into battle."

U.S. embassies in the Gulf and Egypt are calling for vigilance after a post on a jihadist website encouraged attacks on American and other international schools there, specifically teachers.

The warnings have been issued by missions in Egypt, Kuwait, Oman, Saudi Arabia and the United Arab Emirates.

U.S. Secretary of State John Kerry hit out Thursday at reported insults by an American official against the Israeli prime minister, saying it was "disgraceful, unacceptable and damaging."

Kerry also pledged that the United States would continue to work "quietly and effectively" in order to relaunch the peace process with the Palestinians in a thoughtful and even-handed way, saying it was "doable."

The world will know in the coming weeks if Iran can make the "tough decisions" needed for a nuclear deal, U.S. Secretary of State John Kerry said Thursday.

As the clock ticks down to a November 24 deadline for an agreement on reining in Iran's nuclear program in exchange for sanctions relief, Kerry vowed that global powers were going to be "very careful, everything will be based on expert advice."

The U.S. government Thursday backed calls by the family of a Washington Post journalist held in Iran without charge that Iranian authorities should free him.

Jason Rezaian, a dual U.S.-Iranian citizen who is the newspaper's Iran correspondent, was arrested at his home in Tehran on July 22, but the allegations against him have never been officially disclosed.

Iran wants all Western sanctions to be lifted before striking a deal on its contested nuclear program by a November deadline, a top official said Wednesday.

The announcement came amid intensifying efforts to conclude a definitive pact. The six powers in the talks with Iran -- Britain, China, France, Russia, the United States plus Germany, known as the P5+1 -- have set November 24 as the deadline.

The White House's unclassified computer network was recently breached by intruders, a U.S. official said Tuesday, with The Washington Post newspaper reporting that the Russian government was thought to be behind the act.

"In the course of assessing recent threats, we identified activity of concern on the unclassified EOP network," said the White House official, speaking on condition of not being named.