Top State Department officials are vowing to improve security at U.S. diplomatic posts around the world, some before the end of the year.

Those promises were repeated Thursday in Washington in a hearing before the Senate Foreign Relations Committee, the first of two sessions in which Deputy Secretaries of State William Burns and Thomas Nides testified about the deadly attack on the U.S. consulate in Benghazi, Libya.

"We've learned some very hard, and painful lessons in Benghazi, and we are already acting on them," Nides told senators. "We have to do better."

The two testified the State Department deployed five teams to assess security at 19 U.S. diplomatic posts in 13 countries. They said the department partnered with the Pentagon to send 35 additional Marine detachments -- about 225 Marines -- to medium- and high-threat posts with the hope the additional Marines would be deterrents against any attack attempts.

Also, the department wants to hire more than 150 diplomatic security personnel -- an increase of 5% over current staffing -- and provide them with equipment and training.

The hearings follow a scathing independent report released Tuesday that blamed "systemic failures and leadership and management deficiencies" for inadequate security amid the attack that killed four Americans, including Ambassador Chris Stevens.

This week's report and hearings mark a significant chapter in the winding saga surrounding the events of September 11, 2012. That night, the consulate became engulfed in flames. Cameras captured images of a huge crowd of people in the streets -- some waving Libyan flags -- around the consulate, before gunmen descended on the compound.

The assault was ultimately determined to be a terrorist attack.

Stevens, a lifelong diplomat admired by many of different political parties, had previously written diplomatic correspondence warning that al Qaeda-linked militants were growing in strength in an enclave not far from the city.

Burns' and Nides' appearance on Capitol Hill marks the first time officials of their level have spoken about the attack.

Both are top advisers to Secretary of State Hillary Clinton, who is not able to testify because she is ill. Clinton ordered the review in the aftermath of the attack. Such reports are mandated by Congress when Americans working on behalf of the U.S. government are killed overseas.

The 39-page unclassified version of the report concludes that the leadership failures resulted in a security plan "that was inadequate for Benghazi and grossly inadequate to deal with the attack that took place."

Nides told senators he's leading a task force to implement 29 recommendations in the review board report. Some of the recommendations will be implemented before the end of the year.

"We accept every one of them," Nides said.

"The undersecretary of political affairs, the undersecretary for management, the director general of the Foreign Service and the deputy legal adviser will work with me to drive this forward," Nides said.

The task force has already met to translate the report's recommendations into 60 specific action items, he told senators. "We've assigned every single one to the responsible bureau for immediate implementation, and several will be completed by the end of this calendar year," he said.

He promised to work with Congress to make sure those recommendations become reality.

Four State Department officials were disciplined after the release of the report. One resigned, and three others have been placed on administrative leave, spokeswoman Victoria Nuland said.

On Thursday, Nides also asked that Congress provide the department with more money to pay for ramped-up security.

Sen. John Kerry, widely considered the leading candidate to succeed Clinton, seemed to agree that the department should get more funds.