U.S. Defense Secretary Ash Carter told ABC News overnight that a bomb is a "possible reason" that the Russian airliner crashed over Egypt last weekend, but said he "understand[s] that there are other hypotheses."

Speaking to ABC News' Bob Woodruff aboard the USS Theodore Roosevelt in the South China Sea, Carter appeared to cautiously back up claims from top British officials that a bomb was a likely culprit, Carter saying that theory was "consistent with what we know," but also indicated other explanations for the crash could also be "consistent with what [the U.S. government] know[s]."

Beyond that, Carter said, "We don’t have information to share with you on that."

'Significant Possibility' Russian Plane Was Brought Down by Explosive Device, UK Says

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Late Wednesday, British Foreign Secretary Philip Hammond said that while the investigation is on going, there was a "significant possibility" the crash was caused by a bomb, and Britain was suspending flights to and from the Sinai resort of Sharm el-Sheikh, the plane's origin, indefinitely.

Early this morning Egyptian authorities fired back at those comments, saying they "have to move quickly to stop these allegations."

"This is only meant to hurt tourism and strike economy," Egyptian Gen. Khaled Fouda, the governor of South Sinai, said. "We have to wait for the results of the black box and those who don't want to wait are biased."

Fouda reiterated earlier claims that the plane "had many problems" and could have gone down due to mechanical failure.

A Russian Foreign Ministry spokesperson said today the Russian government too was "shocked" by the British allegations and said they will wait for the investigation to take its course. Whatever intelligence the British are using to make their assessment, the spokesperson said, was not being shared with the Russian government.

Late Wednesday several U.S. officials indicated to ABC News that they were eyeing an explosive as one possible cause of the crash that killed more than 200 people, but they had not come to a final determination.

Hours after the deadly crash Saturday, an affiliate of ISIS claimed credit for downing the plane -- a claim initially dismissed by many security officials.

Seth Jones, Director of the International Security and Defense Policy Center at the defense think tank Rand Corporation, said there are "indications" the Sharm el-Sheikh airport itself "may have been compromised" by ISIS.

Carter told ABC News that ISIS involvement in the tragedy was "always a possibility."

Some 20,000 British tourists are believed to be in Sharm el-Sheikh, but British Foreign Minister Hammond told BBC Radio that the government suspended flights home because it was not satisfied with security arrangements at the airport there.

Egypt's Gen. Fouda said that the airport is "equipped with highly-sophisticated equipment."

Editor's Note: A previous version of this report identified a U.S. Navy ship as the USS Roosevelt. It is the USS Theodore Roosevelt.