Russia and China are spying on US facilities at close to Cold War levels, the head of US intelligence has warned.
Mr McConnell said extended surveillance powers were 'critical'
Both were aggressively collecting information on the US, head of National Intelligence Michael McConnell warned.
US agencies are battling traditional state foes as well as terror groups, Mr McConnell told a congressional hearing.
Mr McConnell was defending new legislation allowing the US government to eavesdrop on international phone calls and e-mails without a warrant.
"Foreign intelligence information concerning the plans, activities and intentions of foreign powers and their agents is critical to protect the nation and preserve our security," Mr McConnell told the House Judiciary Committee.
Wire tapping without a warrant has been a contentious issue since the US Congress passed new anti-terror laws in August.
The Protect America Act allows the government to eavesdrop on foreign communications, even if the recipient is a person living in the US.
These powers are due to expire in January unless Congress extends them.
The White House wants them made permanent.
But opponents - including civil liberties groups - say an extension could erode privacy rights and give the government unrestricted power to spy on its own citizens.
Mr McConnell told Congress the powers were crucial to preserving national security.