JACKSONVILLE, Fla. -

U.S. Sen. Bill Nelson, D-Florida, spoke Wednesday at his Jacksonville office about the beheadings of American journalists by ISIS.

The militant group ISIS claims President Barack Obama deserves the blame for the two video recorded executions, calling America's foreign policy "arrogant."

Nelson said it's time for a unified U.S. government to support the White House.

"So this is a terrorist group, the likes of which we have not dealt with before, and we better stop them now because we'll have to be dealing with them in the future," Nelson said.

Steven Sotloff's execution has stirred anger, disgust and determination.

"As a nation, we're united, and when people harm Americans, we don't retreat, we don't forget," Vice President Joe Biden said. "We take care of those who are grieving, and when that's finished they should know we will follow them to the gates of hell until they are brought to justice."

"They line up prisoners and slaughter them," Nelson said. "They behead people with no jury trial. They took the city of Mosul in northern Iraq, and lo and behold, the Iraqi army turned tale and ran. As a result, they have all of those American weapons we had given the Iraqi army."

Nelson announced plans to introduce legislation next week on Capitol Hill fully and legally authorizing President Obama to launch airstrikes against ISIS in Syria as well as Iraq.

Nelson said he has support from other senators like John McCain, and he said the reasons for action are obvious.

"I had hoped that the president would realize that this kind of barbarity only brings home what we face and the scope of it. Unfortunately, that doesn't seem to be the case," said Sen. John McCain, R-Arizona.

"They've shown their true colors, and that's why we better go after them now, because we're going to be dealing with them in the future," Nelson said.

Secretary of State John Kerry said Wednesday the country's effort for diplomacy continues and that his prayers remain with the families of all hostages who remain trapped in Syria.