The U.S. House has passed its version of the defense policy bill for fiscal year 2018 but not before debate on requiring a longer timeline to review the costs of modernizing the U.S.'s nuclear weapons and delivery systems.

The bill passed the House by a vote of 344-81 on Friday.

The measure authorizes $8 billion for submarine programs, including $1.9 billion for the development and design of the first Columbia-class ballistic missile submarine.

The Columbia-class submarines are referred to as the most survivable leg of the U.S. nuclear triad, which also includes manned bombers and long-range intercontinental ballistic missiles, because of their ability to hide in the depths of the ocean. The Columbia submarines, the replacement for the current Ohio-class ballistic missile submarines, will carry 70 percent of the U.S.'s active nuclear arsenal.

Proposals to complete a more comprehensive study of the projected cost of nuclear forces were stymied. California Democrats Reps. John Garamendi and Paul Aguilar introduced two separate amendments to extend a required Congressional Budget Assessment cost estimate from a 10-year period to 30 years. Those amendments didn't pass.

"The more information, the better," said U.S. Rep. Joe Courtney, D-2nd District, when asked whether he supported requiring a longer timeline.

An amendment introduced by Alabama Republican Rep. Mike Rogers to allow the secretary of defense to provide information beyond the 10 years, if the "secretary determines that such information and data is accurate and useful in understanding the long-term nuclear modernization plan," did make its way into the bill.

Officials frequently cite $1 trillion as the estimate for modernizing the nuclear triad over the next 30 years. The Congressional Budget Office currently is in the process of doing its own 30-year-assessment, which is reportedly expected to put the estimate at $1.2 trillion. The $1 trillion modernization effort began under the Obama administration, which left the Trump administration with many of the big budgetary decisions of how to do that.

"It's a big price tag and there's a lot of discussion and debate about how we pay for all this. I feel very strongly that the sea based piece of it is the most solid in terms of people's understanding," Courtney said. "Even if you talk to some of the members that you would put in the camp of strongest for disarmament or scrutinizing the Pentagon, there really is universal acknowledgement that the sea based leg is the most essential."

Washington Democrat Adam Smith has raised the possibility of not upgrading all three legs of the triad at the same time. He has called for delaying certain budget requests until the Trump administration completes its nuclear posture review.

The administration is conducting the review "to ensure that the United States nuclear deterrent is modern, robust, flexible, resilient, ready and appropriately tailored to deter 21st-century threats and reassure our allies." Defense Secretary Jim Mattis wants it done in six months, which would mean it'd be completed in the fall.

"That's pretty ambitious," said Stephen Schwartz, a longtime nuclear weapons analyst, adding that an effective, thorough review that would make it any way different from the current trajectory can't be done in that timeframe.

Recent 10-year snapshots have made the expenditures seem manageable, but "as we get more into modernization, the mountain gets taller," Schwartz said.

"As a practical matter, Congress' planning horizon is usually as long as the next election," he added. "You can't get them to think seriously about 10 years, let alone three."

j.bergman@theday.com