The international community must be ready to use military action in response to any chemical weapons use by the Syrian regime, Israel's deputy foreign minister said on Friday.

"From the moment the international community understands that red lines have been crossed and that chemical weapons have been used, they will realize there's no other choice than to react (militarily)," Zeev Elkin told Israeli army radio.

British Prime Minister David Cameron said on Friday that growing evidence of the use of chemical weapons by the Syrian regime was "extremely serious".

He agreed with U.S. President Barack Obama that such use would represent a "red line" for the international community, but said the response would likely be political rather than military.

The U.S.'s top military officer said in Japan Thursday that his troops were ready to act if North Korea turned its increasingly bellicose rhetoric into action.

"We are seeking to deter North Korea from provocation," General Martin Dempsey, chairman of the Joint Chiefs of Staff, told soldiers at the Yokota Air Base, about an hour's drive west of the Japanese capital.

Russian President Vladimir Putin expressed hope that the Boston bombing tragedy would result in closer cooperation between Moscow and Washington in the fight against terror.

"I hope this tragedy pushes us closer to one another in stopping shared threats," Putin said during his live televised call-in session in Moscow, saying Russia was also a victim of "international terrorism".

Authorities in Bahrain, which has been hit by Shiite-led protests for two years, have voiced "dismay" over an assessment by the U.S. State Department of the rights situation in the kingdom.

"The report includes texts which are totally far from the truth, adopting a manner that fuels terror and terrorists targeting Bahrain's national security," state news agency BNA late on Wednesday quoted government spokeswoman Samira Rajab as saying.

Dutch officials pulled armed police from secondary schools in the western city of Leiden on Wednesday as they lowered the level of an alert over an online threat to carry out a school shooting.

The threat to "shoot my Dutch teacher and as many students as I can" made on a U.S.-based website over the weekend led to all secondary schools in the university city being closed on Monday and police being deployed.

A former personal secretary to Osama bin Laden got a strong rebuke from a judge Tuesday as he was sentenced to life in prison for a second time after claiming the Sept. 11 attacks and Superstorm Sandy were "God's punishment" for injustice against himself and others by the United States.

"You sir, in my judgment, are a committed terrorist who has betrayed his country," U.S. District Judge Lewis A. Kaplan told Wadih El-Hage after listening to the claims of the Lebanese-born man who became a U.S. citizen.

U.S. Defense Secretary Chuck Hagel arrived in Riyadh Tuesday to seal a major arms deal that will provide the Saudi kingdom with sophisticated missiles for its American-made fighter jets.

Hagel flew in from Jordan after a three-day visit to Israel in his first tour of the region since he took office two months ago.

NATO must review its ability to fend off threats to the alliance from Syria, including the possible use of chemical weapons, U.S. Secretary of State John Kerry said Tuesday.

"We should ... carefully and collectively consider how NATO is prepared to respond to protect its members from a Syrian threat, including any potential chemical weapons threat," Kerry told a meeting of NATO foreign ministers.

The elder of the two brothers allegedly behind the Boston marathon bombings twice attended boxing training events in Austria, the interior ministry said Tuesday.

Tamerlan Tsarnaev, 26, shot dead on Friday by U.S. police, spent a week in Salzburg in 2007 and a week in Innsbruck in 2009, the ministry said, confirming a media report.