The German and French governments have joined forces to combat the Islamic State group, joining a coalition of the European Union, Turkey and the United States.
The EU, which has called on all countries to combat radical Islamic terrorism, has announced the creation of a common terrorism taskforce.
It is also expected to establish a regional coalition of European countries to counter the threat from the IS group.
The German and European Union said they would work together to combat terror.
The US, with the help of France, Britain, Germany and Italy, said it would be “very important” to work with Russia to combat extremism in Syria and Iraq.
In a statement, US President Donald Trump said he wanted to strengthen the fight against extremism, including “extremist groups who threaten peace and stability in the world”.
“As president, I have directed our Department of Homeland Security to develop an action plan to confront these groups and the violent extremists who seek to impose their extremist views,” Mr Trump said.
“The US has taken decisive action against the violent extremist group ISIL (Islamic State of Iraq and Syria, formerly ISIS),” he said.
The White House said Mr Trump had asked the Pentagon to lead the US-led coalition against the Islamic state.
“This action is designed to ensure that the coalition of countries that share common interests will succeed and the ISIL group will be defeated,” it said.
Mr Trump’s statement was echoed by the French President Emmanuel Macron, who said the United Kingdom and France were working together in “a big way” to fight the Islamic group.
“We are united in the fight for stability in Europe and in the Middle East, we are united as allies in the struggle against terrorism and we are working to prevent further terrorist attacks,” Mr Macron said.US and Russian air strikes in Syria, the Islamic Republic of Iran and other countries have killed hundreds of Islamic State fighters.
The European Union is planning a summit in the coming weeks to tackle extremism, and has urged all EU countries to take part in the coalition.
Russia, which is also a member of the coalition, said its air strikes and special forces had hit IS positions, which have been surrounded and retaken by US-backed Syrian government forces.
The Kremlin has said the IS has been trying to create a caliphate in Syria to spread its ideology, and is trying to recruit new fighters from Europe.