World leaders responded to Friday’s bloody attacks in Paris with outrage and defiant pledges of solidarity, but several countries said they would tighten security, especially at their borders, and a few urged their citizens not to travel to France.

Islamic State claimed responsibility on Saturday for the coordinated assault by gunmen and bombers that killed 127 people across Paris. President Francois Hollande said the attacks amounted to an act of war against France.

Several countries said they had stepped up their own security in response to the attacks, including Belgium and Switzerland, which border France. France’s neighbor to the south, Spain, said it was maintaining its state of alert at level 4 on a five-point scale.

Dutch Prime Minister Mark Rutte said the Netherlands would tighten security at its borders and airports, and said the Dutch were “at war” with Islamic State.

“Our values and our rule of law are stronger than their fanaticism,” he said.

Belgium imposed additional frontier controls on road, rail and air arrivals from France and Belgian Prime Minister Charles Michel asked Belgians on Saturday not to travel to Paris unless necessary. Hong Kong also issued a travel alert for France.

Bulgaria imposed additional frontier controls on road and transit traffic.

London Metropolitan Police Service’s assistant commissioner Mark Rowley told the BBC that policing across Britain would be strengthened but said there would be no change to the threat level which currently stood at the second-highest category.

New York, Boston and other cities in the United States bolstered security on Friday night, but law enforcement officials said the beefed-up police presence was precautionary rather than a response to any specific threats.

The United States and Russia, divided on many issues including the war in Syria that has fueled Islamist violence, voiced their support for the French people on Friday night.

“Once again we’ve seen an outrageous attempt to terrorize innocent civilians,” U.S. President Barack Obama said. “We stand prepared and ready to provide whatever assistance that the government and the people of France need.”

“Those who think that they can terrorize the people of France or the values that they stand for are wrong,” Obama said.

CONDOLENCES

Russian President Vladimir Putin sent his condolences to Hollande and all the people of France following the “horrible terrorist attacks in Paris”, the Kremlin said in a statement.

“Russia strongly condemns this inhumane killing and is ready to provide any and all assistance to investigate these terrorist crimes.”

Egypt’s President Abdel Fattah al-Sisi said Egypt stood in solidarity with France and supported counter-terrorism efforts.

“Terrorism recognizes no boundaries or religion, and claims the lives of innocent people in different parts of the world,” a statement from the presidency’s office said.

Saudi Arabia’s highest religious body condemned the attacks as contrary to Islamic values.

“Terrorists are not sanctioned by Islam and these acts are contrary to values of mercy it brought to the world,” said a statement by the Council of Senior Scholars carried by the Saudi Press Agency on Saturday.

The Western defense alliance NATO said it stood with France, a founder member. Secretary-General Jens Stoltenberg said, “We stand strong and united in the fight against terrorism. Terrorism will never defeat democracy.”

In Brussels the leaders of European Union institutions, which have been trying to coordinate security responses since the Islamist attacks in Paris in January, joined the chorus of support.

“I am confident the authorities and the French people will overcome this new trial,” European Commission President Jean-Claude Juncker said.

But in a sign of potential divisions ahead, Poland’s European affairs minister designate said after the attacks in Paris, Warsaw would not be able to accept migrants under European Union quotas.

In September, Poland backed a European Union plan to share out 120,000 refugees, many of them fleeing the war in Syria, across the 28-nation bloc.

Now, “in the face of the tragic acts in Paris, we do not see the political possibilities to implement (this),” said Konrad Szymanski, who takes up his position on Monday as part of a government formed by last month’s election winner, the conservative and euroskeptic Law and Justice (PiS) party.