WASHINGTON (CBSDC/AP) — Democratic Sen. Mark Udall of Colorado doesn’t believe that the Islamic State of Iraq and Syria terror group is an immediate threat to the homeland.

Speaking to KUSA-TV, Udall, a member of both the Senate Armed Service and Intelligence committees, stated that he didn’t want the U.S. to “rush in” to a military conflict against ISIS.

“I take ISIL as a very serious threat,” Udall told KUSA, using an alternate acronym for the Islamic State. “I don’t take ISIL as an immediate threat to the homeland, but this is why it’s so important that we’re knocking them back now with airstrikes.”

Udall explained that President Barack Obama would need to make a case before Congress if he wants to do more than just airstrikes to take on the terror group.

“I am strongly opposed to putting boots on the ground,” Udall told KUSA. “If we’re going to expand our involvement there, the president needs to come to Congress and make the case.”

Udall feels that Arab countries need to stop funding ISIS and that moderate Iraq Sunni groups should play a role.

“ISIL has real capabilities, we need to take them seriously, and we need to be smart about how we tackle the threat they represent,” Udall told KUSA.

Obama administration officials maintained that the U.S. will not launch a ground war against the Islamic State militants. But they stopped short of ruling out airstrikes against the group in its safe haven in Syria, as the U.S. has resisted for years. The U.S. has been conducting airstrikes against ISIS in Iraq.

Obama has “been clear that we’re not going to be limited by geography,” State Department spokeswoman Jen Psaki said. She described a range of actions being considered against the Islamic State, and noted that decisions and discussions were ongoing.

Over the past day, Secretary of State John Kerry and other administration officials have reached out to leaders from Australia, the UAE, Jordan, Qatar, Saudi Arabia, Italy and Israel to discuss how to combat the Islamic State. Psaki said the discussions focused on what each country might contribute — including weapons, humanitarian aid and other resources — and noted that some nations already have.

Obama “wants to build an international coalition,” Psaki said. “That’s not going to be overnight. We need capabilities from many countries.”

During a press conference in Estonia on Wednesday, Obama said the U.S. is looking to “degrade and destroy” ISIS following the beheadings of American journalists Steven Sotloff and James Foley.

“Our objective is clear, and that is to degrade and destroy ISIL so that it’s no longer a threat,” Obama said.

Obama vowed the U.S. would not forget the “terrible crime” against Foley and Sotloff.

“We will not be intimidated. Their horrific acts only unite us as a country and stiffen our resolve to take the fight against these terrorists,” Obama said. “And those who make the mistake of harming Americans will learn that we will not forget, and that our reach is long and that justice will be served.”

Obama also sought to clean up the damage from his statement last week that “we don’t have a strategy yet” for dealing with ISIS in Syria.

“It is very important from my perspective that when we send our pilots in to do a job, that we know that this is a mission that’s going to work, that we’re very clear on what our objectives are, what our targets are,” Obama said. “We’ve made the case to Congress and we’ve made the case to the American people, and we’ve got allies behind us so that it’s not just a one-off, but it’s something that over time is going to be effective.”

Separately, during an appearance in Maine, Vice President Joe Biden declared that the U.S. will pursue the militants to “the gates of hell.”

“As a nation, we’re united. And when people harm Americans, we don’t retreat, we don’t’ forget,” Biden said. “We take care of those who’re grieving and when that’s finished they should know we will follow them to the gates of hell until they are brought to justice. Because hell is where they’ll reside.”

In the Sotloff video, a masked militant warns Obama that as long as U.S. airstrikes against the Islamic State group continue, “our knife will continue to strike the necks of your people.”

“I’m back, Obama, and I’m back because of your arrogant foreign policy towards the Islamic State, because of your insistence on continuing your bombings … and on Mosul Dam, despite our serious warnings,” the executioner said. “You, Obama, have but to gain from your actions but another American citizen. So just as your missiles continue to strike out people, our knife will continue to strike the necks of your people.”

Obama responded that the airstrikes have been effective in blunting the militant threat and he will continue to battle the “barbaric and ultimately empty vision” that the Islamic State represents. He said he will consult with NATO allies at a summit in Wales Thursday and Friday on a strategy to combat the Islamic State and other militant networks that arise.

(TM and © Copyright 2014 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2014 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)