WASHINGTON — US funding for its own missile defense development and Israeli missile defense aid is in competition for limited dollars, a new report from a Washington think tank released Friday finds.

The report from the Center for Strategic and International Studies examined how the Missile Defense Agency's growing responsibility since its inception in 2002 and the expanding "colors of money" it must juggle to fund programs in research and development, procurement and operations and sustainment has put a strain on the agency, especially as defense spending decreases and budget top lines across the Defense Department are on a downward trend.

But another source of the strain is that foreign assistance to help Israel develop its own missile defense since 2009 has more than quadrupled. "Much of the more recent increase has come from procurement of Israeli systems and interceptors like Iron Dome," the report states.

Moreover, Congress has consistently increased the Israel funding beyond what the Pentagon has requested over the course of 10 years, but most significantly over the last five, according to a chart comparing budget requests with congressional additions.

The report states that between 1998 and 2012, about 1 to 3 percent of MDA's budget went toward Israeli cooperative programs. In 2011, that percentage rose to 3.5 during the Israel-Gaza conflict. The funding was devoted to research and development.

In 2014, Israeli missile defense funding took up 9 percent of MDA's budget. The percentage rose because systems being developed were ready for procurement — mainly for Iron Dome batteries and interceptors.

In 2016, David's Sling and Arrow were added into the procurement account in addition to Iron Dome.

And none of this accounts for Congressional additions to the budget for Israeli missile defense cooperation. Congress is again poised to funnel more funding in fiscal 2017 into the account beyond what was budgeted. The administration's request is for $146 million while Congress could bring that amount up to $600.8 million. The House Armed Services Committee's authorization would increase the budget by $450 million, the largest plus-up among the four congressional defense committees.

But while there are advantages to funding Israeli missile development that directly benefit the US, the way it's being funded further hinders what the MDA can focus on with the rest of the money available.

"Year in and year out what tends to happen is that Congress will take a look at the administration's requested amount for Israel and they will add some amount in addition to that," Tom Karako, the principal author of the CSIS report said Friday during a panel discussion on the document. "What happens in the process is that MDA is not really fully made whole in the process. So, year in and year out, what tends to happen is that US programs tend to get cut as a kind of bill payer for a larger Israel program."

MDA's "delta" of a funding increase or, in some cases, decrease each year "is nowhere near enough to cover all US priorities, especially research, technology and development dollars that should be invested now to keep the pace with possible threats particularly from North Korea and Iran in the future, according to Karako.

For instance, congressional defense appropriators in the House and Senate in their 2017 budgets, Karako said, cut some of the "most important advanced technology work that MDA is doing," in order to cover additional funding for Israel.

Among those programs, Karako said, are the Redesigned Exoatmospheric Kill Vehicle (RKV) designed to improve the current US homeland ballistic missile defense system -- the Ground-Based Midcourse Defense System (GMD) -- as well as directed energy development and work on the next iteration of the RKV, the Multiple Object Kill Vehicle.

The CSIS report suggests that "one possible path to avoid competition" between MDA needs and Israeli missile defense needs "would be to transfer Israeli missile defense foreign assistance to another account," such as through Foreign Military Financing (FMF).

"Such a move could alleviate some of the growing tension between US and Israeli missile defense priorities," the report adds. "Unless Congress carefully stewards the combination of Israel and US dollars at every stage, Israeli missile defense and US missile defense dollars will compete with one another."

The deputy director of MDA, US Army Maj. Gen. Ole A. Knudson, defended funding Israel's missile defense efforts, stating, "If you look at the threats that Israel is facing and advances in capability that they have already made and that they believe they need to make in the future, and we are helping them do that. It's a very extreme situation that they face and they've had more missile attacks, I'm certain, than anyone else, so they feel it and so we are very supportive of doing everything we can to advance their capabilities from MDA and you can see that Congress is too."

Even so, "It's a challenge that we don't have an absolute way to predict how [the budget] is going to turn out in each cycle," Knudson added. "Having stability would be better for MDA and so however that stability comes about, whether it's some increased amount, whether it comes out of some different account, I think stability would make a degree of benefit to how we work through this."

Karako also stressed that there is nothing in the report to suggest the US does not support Israel or any allies. "The important thing is really in the appropriations process to make sure that US programs don't serve as the bill payer at the margin, so if moving to a different committee, a different account is a way to get at that, that is a possibility," he said, adding, "these trades are not being made within MDA, they are being made on Capitol Hill."

Twitter: @JenJudson