Nuclear weapons, terrorism and computer spying are problems for national security, say American intelligence officials.
The officials say challenges and crises are more diverse than ever.
James Clapper and Lieutenant General Vincent Stewart oversee national intelligence operations. They spoke to the Senate Armed Services Committee.
Clapper and Stewart said North Korea could soon have enough plutonium to make nuclear weapons. And North Korea has started to develop an intercontinental ballistic missile system -- missiles that could reach other countries.
The officials said Iran is another country with a developing nuclear weapons program. Iran plans to keep its nuclear program, Clapper said, although it agreed in July to halt it. Economic sanctions put into place by six major nations were lifted when Iran agreed to halt its program.
But Vincent Stewart said the Islamic State terror group is the leading international threat.
Islamic State, he said, "will probably attempt to conduct additional attacks in Europe and attempt to direct attacks on the U.S. homeland in 2016."
Both officials said Russian and Chinese computer crime is another big threat.
Clapper told the senators, "Whether China's commitment of last September (to curb its cyber espionage) moderates its economic espionage remains to be seen."
Clapper said Russia is suspicious of being limited by NATO.
"They are greatly concerned about being contained and, of course, very concerned about (the U.S.) missile defense, which would serve to neuter what is the essence of their claim to great power status, which is their nuclear arsenal."
On the same day of the hearing, President Barack Obama announced new measures to enhance cyber security.
I'm Caty Weaver.
Zlatica Hoke wrote this story for VOA. Caty Weaver adapted it for Learning English. Kathleen Struck was the editor.
What do you think are the main security threats facing your country? Post your thoughts in the comments section or on 51VOA.COM.
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Words in This Story
challenge – n. a difficult task or problem: something that is hard to do
diverse – adj. different from each other
commitment – n. a promise to do or give something
espionage – n. the things that are done to find out secrets from enemies or competitors: the activity of spying
essence – n. the basic nature of a thing: the quality or qualities that make a thing what it is