US President Barack Obama addresses a joint news conference with British Prime Minister David Cameron (Not Pictured) following their meeting at the White House in Washington January 16, 2015. [Photo/Agencies]

WASHINGTON - US President Barack Obama and British Prime Minister David Cameron pledged a joint effort Friday to fight domestic terrorism following deadly attacks in France.

Cameron's visit to Washington came one week after 17 people were killed in attacks in France, heightening fears in Europe and the United States about the spread of terrorism.

"This is a problem that causes great heartache and tragedy and destruction," Obama said in a joint news conference with Cameron. "But it is one that ultimately we are going to defeat."

The prime minister was blistering in his assessment of those responsible for the attacks, calling them part of a "poisonous, fanatical, death cult."

"We know what we're up against, and we know how we will win," Cameron said. He spoke as British police chiefs announced that the Paris attack on a kosher supermarket and anti-Semitic rhetoric from extremists had led them to study ways to increase protection for the Jewish community.

The prime minister arrived in Washington with a request for Obama to help persuade US technology companies to give governments more access to encrypted communications that terrorists may use to plot attacks.

Cameron's policy proposals have stoked concern on both sides of the Atlantic about the prospect of security efforts encroaching on privacy, particularly in the wake of the 2013 spying disclosures by former NSA contractor Edward Snowden.

"As technology develops, as the world moves on, we should try to avoid the safe havens that would otherwise be created for terrorists to talk," Cameron said.

Obama didn't take a position on Cameron's proposal, but he did say it was important to be able to keep tabs on terrorists who are using social media and the Internet.