The Senate is set to begin debating the country’s annual defense policy legislation, a perennially controversial task lawmakers hope to wrap up by Thanksgiving.

The defense authorization act is rife with contentious assumptions about the nature of warfare and the country’s defenses — and myriad other national security policy issues — but lawmakers have made a point of passing the policy legislation every year for the past 51 years, even when they couldn't pass budgets.

The House in June passed its version of the 2014 National Defense Authorization Act, but the Senate still needs to resolve a host of issues, including:

Sexual assault: The debate over how to curb about 26,000 sexual assaults a year in the military has no distinct partisan lines. Republicans and Democrats are split on how to combat the problem. Sen. Kirsten Gillibrand, D-N.Y., is pushing legislation that would relieve military commanders of the authority to decide who should be prosecuted for such crimes. But top Armed Services Committee Democrats, including Chairman Carl Levin, of Michigan, and Sen. Claire McCaskill, of Missouri, insist that commanders remain part of the process.

Gillibrand needs to win over 60 votes to get her proposal attached to the defense bill.

Iran sanctions: Negotiations over Iran's nuclear program collapsed in Geneva recently, and Sens. Mark Kirk, R-Ill., and Robert Menendez, D-N.J., are now weighing whether to respond by tightening U.S. economic sanctions on Iran. Tightening financial prohibitions, the senators said, could increase pressure on Tehran to abandon its nuclear ambitions.

Kirk and Menendez could press for new sanctions through the Senate Banking Committee, but they also may try to attach them to the defense bill. The Obama administration opposes any new sanctions, insisting they could undercut negotiations with Iran.

Sequestration: After a round of automatic budget cuts this year, the Pentagon made clear that further cuts would do serious, self-inflicted damage to the country’s military readiness. These automatic cuts, known as sequestration, are scheduled to shave more than $50 billion from the Pentagon's budget in January 2014 unless Congress acts to replace the funding.

There is bipartisan opposition to sequestration, but there is far less agreement on how to replace the cuts. There may a largely symbolic effort to use the defense bill to eliminate the cuts, lawmakers appear more likely to increase flexibility for the Pentagon and other agencies to decide where the cuts should be made.

Guantanamo Bay: The Guantanamo Bay detention facility in Cuba still holds 164 suspected terrorists and an earlier version of the defense bill barred those detainees from being brought to the United States for either trial or incarceration. But President Obama has renewed his push to relocate the detainees and close the facility. Democrats are now trying to convince Republicans to back the closing by emphasizing the operating costs at Gitmo.

“We are spending almost $1 million per detainee per year to house detainees at Guantanamo," White House press secretary Jay Carney said. "That’s nearly $200 million dollars annually in an era of sequestration and tighter budgets.”

Base closures: The decision to consolidate and eliminate military bases has had a profound economic effect on communities around the bases. Still, military leaders looking to cut costs appear open to holding another round of base closings, something political leaders oppose. The House version of the defense bill explicitly prohibits another round of closings, and the Senate is expected to follow suit ahead of the 2014 elections.

East Coast missile shield: Senate Republican hawks have been pushing for the construction of an East Coast missile shield to protect against missile attacks, particularly from North Korea or Iran. The House version of the defense bill calls for funding towards the project despite assurances from top Pentagon leaders that the shield, expected to cost $3 billion, is not a "military requirement."