Despite progress in fighting terrorism, the threat today may be greater than ever before because the available weapons are far more dangerous, US Defense Secretary Donald H. Rumsfeld said Thursday. "The enemy - while weakened and under great pressure - is still capable of global reach, still possesses the determination to kill more Americans - and still trying to do so with increasingly powerful weapons," Rumsfeld said at the National Press Club. The US strategy, he said, includes doing everything possible to prevent the enemy from gaining weapons of mass destruction, improving homeland defense and intelligence gathering and helping friendly nations become better able to fight the terrorists in their own countries. "Because they lurk in shadows, without visible armies, and are willing to wait long periods between attacks, there is a tendency to underestimate the threat they pose," said Rumsfeld. He said there are no fewer than 18 organizations, loosely connected with al-Qaida, conducting terrorist attacks. Rumsfeld described the stakes in stark terms. "They will either succeed in changing our way of life, or we will succeed in changing theirs," he said.