In an op-ed in The Wall Street Journal, the president said "critical infrastructure networks" have not been disrupted or damaged, but "foreign governments, criminal syndicates and lone individuals are probing our financial, energy and public safety systems every day."
"Last year, a water plant in Texas disconnected its control system from the Internet after a hacker posted pictures of the facility's internal controls," he said. "More recently, hackers penetrated the networks of companies that operate our natural-gas pipelines. Computer systems in critical sectors of our economy -- including the nuclear and chemical industries -- are being increasingly targeted."
Obama said an adversary "in a future conflict" might compensate for battlefield military inferiority by exploiting "our computer vulnerabilities here at home."
"Taking down vital banking systems could trigger a financial crisis," the president said. "The lack of clean water or functioning hospitals could spark a public health emergency. And as we've seen in past blackouts, the loss of electricity can bring businesses, cities and entire regions to a standstill."
Obama said his administration has made cybersecurity a priority, "proposing legislation to strengthen our nation's digital defenses. It's why Congress must pass comprehensive cybersecurity legislation."
"We need to make it easier for the government to share threat information so critical-infrastructure companies are better prepared," he said. "We need to make it easier for these companies -- with reasonable liability protection -- to share data and information with government when they're attacked. And we need to make it easier for government, if asked, to help these companies prevent and recover from attacks."