The US president and other world leaders have condemned a series of coordinated attacks in the French capital Paris that has left more than 100 people dead.
In a statement late on Friday evening, Barack Obama said the attacks were an "outrageous attempt to terrorise civilians" and that his country was ready to provide France with any help it required.
"France is our oldest ally, the French people have stood by the American people time and again, we want to be very clear that we stand together with them in the fight against terrorism and extremism," he said.
Related: World leaders express condolences
"We're going to do whatever it takes to work with the French people and nations around the world to bring these terrorists to justice and to go after any terrorist networks that go after our people."
Obama said he would not speculate on who was responsible for the attacks, which struck multiple locations across Paris, including the Stade France football stadium, where the French team was playing Germany in a friendly match, and the Bataclan art centre, where scores were shot dead.
A statement released by the US Department of Homeland Security said it was closely monitoring the situation in France but was not aware of "specific or credible threats of attack" on US territory.
Obama's comments were echoed by David Cameron, British prime minister, and other world leaders, who took to social media to express their solidarity.
IN PICTURES: Coordinated attacks in Paris
"I am shocked by events in Paris tonight. Our thoughts and prayers are with the French people. We will do whatever we can to help," Cameron wrote in a tweet shortly after news of the attacks broke.
A statement by the German foreign office on behalf of Chancellor Angela Merkel said she was "deeply shocked" by the attack and conveyed her sympathy and solidarity.
Frank-Walter Steinmeier, German foreign minister, was pictured sitting next to French President Francois Hollande during the match at the Stade France.
Russian President Vladimir Putin also expressed his condemnation following the "horrible terrorist attacks", sending his condolences to the French people and Hollande in a statement published by the Russian foreign ministry.
"Russia strongly condemns this inhumane killing and is ready to provide any and all assistance to investigate these terrorist crimes," Putin said.
Justin Trudeau, the recently elected Canadian prime minister, said his government was offering its help to France and that he had discussed the security situation in his own country with officials.
"I've been speaking with our national security team to ensure everything is being done to keep people safe," Trudeau said, according to the National Post newspaper.
Iran's President Hassan Rouhani joined Western counterparts in condemning the attack and the "evil scourge of terrorism", the state-owned Press TV reported.
"I strongly condemn these inhumane crimes and condole with the bereaved French nation and government," Rouhani said.
The attacks on Friday were the latest in a series of deadly incidents the country has experienced this year.
Programme: France's 'Muslim problem'
In January, the offices of the Charlie Hebdo magazine in Paris were attacked by armed men claiming allegiance to al-Qaeda.
The attack left 12 people dead and was quickly followed by an attack on a kosher supermarket in the city, which killed four people.
In March, Germanwings Flight 9525 came down in the French Alps, killing all 150 people on board after what investigators suspect was a deliberate act by one of its pilots.
|A woman leaves flowers at a makeshift memorial outside the consulate of France in New York [Reuters]
Source: Al Jazeera