The European Union (EU) on Monday, in a statement marking the fifth anniversary of the Sep 11, 2001 attacks on the US, said while the fight against terrorism is a priority for the bloc, any measures taken must comply with international law.
The EU "solemnly remembers the many victims, renews its sympathy to their families and friends, and reiterates its condemnation of all forms of terrorism," the EU's Finnish presidency said.
Finland currently runs the rotating presidency of the 25-nation bloc.
Terrorism "poses a serious threat to our security, to the values of our democratic societies and to the rights and freedom of people, especially through the indiscriminate targeting of innocent people," the EU said.
"No cause, no grievance, can justify acts of terrorism," it stressed.
The EU vowed to continue cooperation with the US and other partners in fighting terrorism.
However, "any measures undertaken to prevent and combat terrorism must comply with obligations under international law, in particular international human rights law, refugee law and international humanitarian law," the EU underlined.
In addition, terrorism could only be defeated in the long-term if "conditions conducive to the spread of terrorism" are successfully tackled, the bloc's statement said.
The EU welcomed the recent adoption of the UN global counter-terrorism strategy. The bloc "is committed to contributing to global security and building a safer world".