US President Barack Obama feted three Americans who helped thwart a train attack in France, welcoming them to the White House and hailing their courage.
French President Francois Hollande, whose country is carrying out surveillance flights over Syria, said it would be "necessary" to carry out air strikes against Islamic State militants there.
Hundreds of people waving American flags lined the streets of Sacramento to pay tribute to three local heroes who helped thwart a train attack in France.
A first group of around 50 refugees arrived in France from Germany as Paris tries to ease pressure on its neighbour, which has received the bulk of the migrants streaming into Europe.
Ministers and diplomats from 57 countries gathered in Paris to discuss the make-or-break issue of finance in a climate rescue deal to be sealed in the French capital in December.
France's divisive economy minister has once again made waves among Socialists by criticising the country's sacrosanct 35-hour week just as the ruling party gathers for its annual conference.
UN Secretary General Ban Ki-moon said that countries must "accelerate the rhythm of negotiations" on capping global warming ahead of an international climate conference in Paris in December.
Interior and transport ministers from EU countries are to hold talks in Paris to discuss security measures following last week's attack on a high-speed train that was foiled by passengers.
President Francois Hollande warned that France must brace for further attacks, just days after a potential bloodbath on a train was foiled by passengers.
The US serviceman who was wounded while foiling a gun attack on a train in Europe will be nominated for the Air Force's highest medal for non-combat bravery.
German Chancellor Angela Merkel and French President Francois Hollande called for a "unified" response to the worst refugee crisis to hit the EU since World War II.
Three American friends who overpowered a heavily-armed gunman in a train poured cold water on his claim that he had no intention of waging a bloody attack.