James Clapper, the director of national intelligence, and Ray Odierno, the US Army’s chief of staff, have both decried the impact of the government shutdown. Clapper has called employees’ unpaid furlough a recruitment ‘dreamland’ for foreign spy agencies.

"I've never seen anything like this. In my view I think this, on top of the sequestration cuts, seriously damages the safety and security of the nation," the DNI told a Senate Judiciary Committee hearing that was intended as a discussion of NSA surveillance powers.

Officials say that about 70 percent of all intelligence personnel have been forced to take unpaid leave, including 4,000 computer specialists.

“This affects our global capability to support the military, to support diplomacy, and to support our policymakers. And the danger here, of course, that this will accumulate over time -- the damage will be insidious. So each day that goes by, the jeopardy increases," said Clapper.

The official said intelligence agencies are setting up financial counseling for staff at a time of unusual vulnerability.

"This is a dreamland for foreign intelligence services to recruit, particularly as our employees, already many of whom subject to furloughs driven by sequestration, are going to have, I believe, even greater financial challenges,” said Clapper.

General Ray Odierno has said that the first government shutdown since 1996, "impacts significantly day-to-day operations" of the US Army.

"The longer it goes on, the worse it gets. Every day that goes by, we are losing manpower, we are losing capability,” the chief of staff told Reuters from Germany.

The army is currently furloughing “non-essential” personnel – particularly those not involved in live operations abroad.

The shutdown, which has forced 800,000 government employees to stay at home, began on Tuesday, after Congress failed to agree next year’s budget. The central bone of contention has been the funding of Obamacare, a scheme to widen health insurance coverage in the US.

Senator Ted Cruz, one of the most vehement opponents of Obamacare, has said that Congress should pass a special amendment that will exempt the army and security services from the shutdown.

"If God forbid, we see an attack on the United States because the intelligence community has not been adequately funded, every member of this committee would be horrified," said Cruz in front of the Senate Judiciary Committee.

Attempts in the past two days to push through various piecemeal mitigations of the shutdown have failed to garner enough votes.