WASHINGTON - America has failed for too long to adequately protect the security of its computer networks, President Obama said yesterday as he announced that he would name a new cyber czar to press for action.

Surrounded by a slew of government officials, aides, and corporate executives, Obama said the United States had reached a "transformational moment" when computer networks are probed and attacked millions of times a day.

"It's now clear this cyber threat is one of the most serious economic and national security challenges we face as a nation," Obama said, adding, "We're not as prepared as we should be."

He said he would soon pick the person he wants to head a new White House office of cyber security, and that person will report to the National Security Council and the National Economic Council - a nod to his contention that the country's economic prosperity depends on cyber security.

Obama's announcement came as the Pentagon is poised to create a cyber command to improve protection of military networks and coordinate its offensive and defensive cyber missions.

Officials have grown increasingly alarmed as U.S. computer networks are constantly assailed by attacks and scams, ranging from nuisance hacking to more nefarious probes and attacks, including suspicions of cyber espionage by other nations.

Officials this year revealed there was a computer attack against the nation's electrical grid, and, separately, computers at the Pentagon were infected by a virus.

The cyber security effort will not involve any monitoring of private networks or individual e-mail accounts, the president said.