The roller-coaster ride is about to begin for defense spending, and it promises to be long and bumpy.

On Thursday, subcommittees of the House Armed Services Committee begin to mark up the fiscal 2013 Defense Authorization Bill. This will be the ride up because the Republican-controlled panel has indicated that it will add about $8 billion to the $546 billion set by the 2011 Budget Control Act (BCA). President Obama, Defense Secretary Leon E. Panetta and the Joint Chiefs of Staff supported the BCA, but the president’s budget is $3.7 billion above the BCA figure. That’s because it includes security spending for agencies other than the Pentagon.

For its core fiscal 2013 budget, the Pentagon produced a new strategic plan as well as proposed reductions next year — $6 billion from this year’s spending. It went farther, too: a total of $487 billion over the next 10 years. However, understand that after 2013, those deep cuts are from increases already built in to spending over those years.

Fiscal 2013 is the only year that defense spending under Obama will actually be cut from a previous year. From fiscal 2013 on, the defense budgets will continue to grow, just not as fast as planned.

Under the House GOP plan, fiscal 2013 defense spending would be at the same rate as this year, but its future increases would grow at a faster pace than in the president’s plan.

So what types of things do the House Republicans on these Armed Services subcommittees want to increase?

Perhaps we can say the first shot in the budget battle was fired Wednesday, when the subcommittee on military personnel put out what is called “the chairman’s mark,” the basic plan worked out by Rep. Joe Wilson (R-S.C.). It will be the basis for discussion and amendments Thursday before Wilson’s subcommittee.

One change that Wilson wants to make is to continue the use of 18 Air Force Block 30 RQ-Global Hawk unmanned surveillance aircraft. The president canceled an additional purchase of 24 of the $200 million aircraft and wanted to put the 18 already purchased in storage. The plan was to save some $2.5 billion over five years. The justification was that the older, piloted U-2 airplane does the same job and has better imaging capability.

Since Wilson’s panel controls only personnel, his “marked” bill just adds 560 people to the strength of the Air Force “to reflect the corresponding manpower requirements to maintain” the 18 Global Hawks that might be retired. Another House Armed Services panel would have to add the funds to operate and maintain the Global Hawks. A committee spokesman said he was unable to say how much that would cost. But a budget expert estimated that the House plan would require an additional $800 million in fiscal 2013 and $2.4 billion over five years, assuming that the U-2s were retired.

The increase may make it through because it has some bipartisan support. Rep. Norm Dicks (Wash.), ranking Democrat on the House Appropriations Committee, criticized the Air Force for agreeing to the Obama plan. He said during a hearing, “I’m worried . . . we already bought them and we need to find some way to get some utilization out of them.”

Another possible change from Wilson’s “mark” is language that would “make clear that non-monetary contributions to health-care benefits made by our troops and their families through a career of service to America represents pre-payment of health-care premiums in retirement.”

Wilson opposes the plan to raise fees for medical care for 9.65 million Tricare beneficiaries. Most of those fees would apply only to working-age retirees and would in part be based on their current income.

The strategic subcommittee “mark” has added nearly $500 million for the Iron Dome program, a short-range missile defense program conducted jointly with Israel. The money is to be spent between 2013 and 2015 and would bring to $900 million the U.S. contribution. The Iron Dome system has proved successful in intercepting recent short-range missile attacks on Israel and probably would have bipartisan support.

The Republicans on the House Armed Services Committee hope to get their overall bill marked up before summer and expect the Democratic-run Senate Armed Services Committee to complete its version by then, too. That would allow a conference between the two bills to be completed by September and passage before Congress adjourns for the November elections.

By September, there also will have to be some settlement of fiscal 2013 appropriations, with a continuing resolution covering all those departments whose individual bills have not passed.

Then there is the Dec. 31 deadline for dealing with the Bush income tax cuts, both for middle- and upper-income people.

Adding to all that, neither party has produced a solution for the additional deficit-reduction program of $1.2 trillion in increased revenue or cuts over the next 10 years required under the BCA. Otherwise, sequestration, the automatic reduction of some $600 billion in security and an additional $600 billion in non-security spending must be made starting Jan. 3.

It is not a good time to be a Pentagon planner or program manager.

For previous Fine Print columns, go to washingtonpost.com/fedpage.