WASHINGTON - The US Senate approved its annual defense policy bill late ?Thursday despite partisan rancor, agreeing to reform the way the military justice system responds to sexual assaults and boosting the Pentagon's ability to help destroy Syria's chemical weapons.

The Senate approved the National Defense Authorization Act on an 84-15 vote, sending the measure to President Barack Obama for his signature after 30 hours of deliberation that involved very little debate and much expression of anger by lawmakers barred from offering amendments.

"This is a big, important, profoundly significant piece of legislation, yet it's being jammed through here in about 24 hours without any opportunity to offer amendments," said Republican Senator John Cornyn of Texas.

Some lawmakers accused the chamber's Democratic leadership of stifling debate to avoid a measure on new Iran sanctions that might embarrass the Obama administration at a time when it is trying to negotiate a solution to Tehran's nuclear program.

Determined to have a debate anyway, Republican Senators John McCain and Lindsay Graham engaged in a discussion about Iran's nuclear enrichment, which Tehran says is for peaceful purposes but Washington believes is aimed at developing nuclear arms.

"Here's the basic question for us as a nation and the world at large: Do you believe the Iranians when they say they're not trying to develop a nuclear weapon ... ? Do you believe them when they make that claim given the reality of their enrichment program, their lying, their cheating," Graham asked.

The legislation approved by the Senate is a huge bill that authorizes everything from overall defense spending levels and military pay to procurement of weapons systems and military-related foreign policy issues.

This year's final measure included more than 30 provisions aimed at overhauling the military's response to sex crimes, giving greater support to victims and reforming the military justice code to enable a tougher response to the crime.

Senator Clair McCaskill, who had advocated additional changes that were not included in the final bill, said the measure represented "a huge win" for sexual assault victims but added "this is no finish line."

"In the months and years ahead, vigilance will be required to ensure that these historic reforms are implemented forcefully and effectively," she said.

The reforms strip commanders of their power to overturn the sentences of a trial by court martial. They eliminate a five-year statute of limitations on rape and sexual assault and establish minimum sentencing guidelines for those found guilty of sex crimes.

The changes also will ensure victims are represented by special attorneys to help them protect their own rights. And they make retaliation against people who report sexual offenses a separate crime.

The bill did not include an additional proposal by Senator Kristen Gillibrand, who is seeking to put decisions about prosecuting sex crimes in the hands of specialized attorneys rather than a victim's commanders, a measure opposed by military leaders.

The bill includes authorizations for the Pentagon to help in the effort to destroy Syria's chemical weapons stockpiles, as well as funding to pay for the effort.

The act makes it easier for the White House to transfer prisoners in the U.S. war against al Qaeda from the facility at Guantanamo Bay, Cuba, to countries willing to accept them.

The act authorizes a Pentagon base budget of $526.8 billion in the 2014 fiscal year. But that amount is about $28 billion more than the $498 billion agreed under the bipartisan budget deal approved by Congress this week and will have to be reconciled in a final appropriations bill early next year.

The authorizations included $17.6 billion for US nuclear weapons programs in the Energy Department and $80.7 billion for the war in Afghanistan and other overseas operations.