The United States has been in constant contact with and offered assistance to Algerian officials in the attack on a gas plant in the Sahara Desert, US President Barack Obama said late Saturday. "The blame for this tragedy rests with the terrorists who carried it out, and the United States condemns their actions in the strongest possible terms," he said in a White House statement. President Obama said the US will "continue to work closely with all of our partners to combat the scourge of terrorism in the region, which has claimed too many innocent lives."