FACTBOX - McCain and Obama priorities on Pentagon weapons

(Reuters) - U.S. presidential candidates Barack Obama and John McCain differ on the size of the U.S. military, the Iraq war and how to deal with Iran, but they have similar views on the need to reform Pentagon procurement.

Both Obama, a Democratic senator from Illinois, and Republican rival McCain, an Arizona senator, have emphasized the need to rein in chronic cost overruns in Pentagon weapons programs, and curb funding for unneeded, outdated weapons systems, but their views diverge on specific programs.

Sceptics say it may be difficult to terminate big programs, but some may become vulnerable to budget cuts.

Following are programs or issues addressed by the candidates:

ARMY FUTURE COMBAT SYSTEMS

Obama said he would slow work on the Army's Future Combat Systems program, a $160 billion (88 billion pounds) modernization effort run by Boeing and Science Applications International.

McCain led a drive several years ago to convert terms of the contract with Boeing and SAIC into a more traditional defence deal, ensuring greater oversight. But he has stopped short of calling for cuts in the program.

MISSILE DEFENSE

Obama supports work on a system to protect the United States and its allies from missile attacks, but says it must be "pragmatic and cost-effective" and cannot divert resources from other priorities until its technologies are proven.