In an interview Wednesday, Pence said the U.S.is "ready to assist in anyway" in response to questions about sending Federal Bureau of Investigation agents.
"People who have long thought of themselves as Saudi's friends are saying this is a very, very serious matter".
The president had been criticised for his mild response to the disappearance of the journalist, with members of Congress imploring his administration try to get to the bottom of the disappearance.
Nauert said Secretary of State Mike Pompeo and other USA diplomats have been engaged on the issue and that Trump himself - he said Tuesday he "knows nothing" about what happened to Khashoggi - intends to speak to the Saudis.
Footage time-stamped 4:51 a.m. and 4:53 a.m. shows the men, carrying small carry-on bags, checking into the Movenpick hotel near the consulate.
It gives the White House 120 days to "determine whether a foreign person is responsible for an extrajudicial killing, torture, or other gross violation of internationally recognized human rights against an individual exercising freedom of expression" and to report back to the Foreign Relations Committee with a decision on how it plans to act.
A source told the Washington Post that United States intelligence "intercepted communications of Saudi officials discussing a plan to capture him".
Turkish officials said the event reminded them of the film "Pulp Fiction", and said one of the men wielded a bone saw they suspect was used to dismember the journalist's body.
Global stocks tumble after Trump 'crazy' Fed comment
The Dow Jones stock market average dropped by 831 points, which is 3.15 percent of its opening value on Wednesday. Tiffany plunged 10.2 percent to $110.38 and Ralph Lauren fell 8.4 percent to $116.96.
The Trump administration is left with an awkward lack of information about a widely respected writer who had been living in self-imposed exile in the USA for the past year after fleeing a crackdown on intellectuals and activists in Saudi Arabia.
But Turkish officials declined to go on record as Turkey tries to manage its hard relationship with regional powerhouse Saudi Arabia.
Rubio said on "America's Newsroom" that if evidence of Saudi involvement is found, there will be an effort in Washington, D.C.to "fundamentally alter" the U.S. -Saudi relationship. Turkish officials say that three of them were members of Crown Prince Mohammed Bin Salman's elite close protection unit.
Boot told Lemon, "If these reports are accurate, they lured (Khashoggi) into their consulate in Istanbul on the soil of a North Atlantic Treaty Organisation country and killed and dismembered him".
Kaye spoke to The Associated Press moments after he and two colleagues called for an global, independent investigation into the disappearance of Khashoggi at the Saudi consulate in Istanbul.
Khashoggi, a Washington Post columnist and frequent critic of the Saudi government, was last seen walking into the Saudi consulate in Istanbul last Tuesday.
The user also labelled Cengiz as part of the "Qatar blockade gang", quoting tweets she had posted in support of the Gulf country after Saudi Arabia and allies severed diplomatic ties a year ago. We have a country that's doing probably better economically than it's ever done before.
He added, "The Saudis continue to claim that they aren't targeting civilians inside Yemen, but how can we believe them when they apparently just hunted down and murdered an American resident whose only offense was writing critical articles about the Saudi royal family?"