In hardball negotiations over the START nuclear arms treaty last year, Senate Republicans wrested a commitment from the White House to redouble work to overhaul the nation’s nuclear infrastructure.

USA/President Barack Obama agreed to spend an additional $5 billion over 10 years on the effort, including some $650 million in the 2011 fiscal year.

The funds would be used to refurbish facilities and upgrade technology to provide safer and more secure devices, for example by making it impossible for them to be detonated if they are stolen by extremist groups. Obama and Senate Democrats even agreed that if it became necessary to cut discretionary spending in the future, the funding for nuclear modernization would be considered on the same basis as defense spending, making it harder to trim.

Somebody should have told House Republicans.

House budget-cutters working on the resolution to fund the government through the end of the current fiscal year in September have eliminated the increased funding for nuclear modernization.

That’s not the last word on it though. Jon Kyl, the No. 2 Senate Republican who led the fight for nuclear modernization, says he will work to add the money back in when the Senate takes up the resolution.