Kicking off a weeklong tour of Middle Eastern and European capitals, Secretary of State John Kerry scrambled to shore up the faltering central government of Iraq as it contends with an increasingly menacing terrorist insurgency.

Kerry landed in Cairo, Egypt on Sunday afternoon amid heavy security and was openly ambivalent about whether the Iraqi government led by Prime Minister Nouri al-Maliki, a Shi'ite, will institute the rapid political changes the U.S. says are necessary for the Iraqi state to survive against the advancing Sunni terrorist group ISIS -- the Islamic State in Iraq and Syria -- which has recently seized control of major Iraqi cities.

A senior State Department official said late Saturday that in addition to pressing Maliki to move expeditiously to form a new government, one that demonstrates inclusiveness toward Shi'ite, Sunni, and Kurdish citizens alike, the secretary of state will also lobby other Arab allies in the Gulf to choke off regional financing for ISIS.

"A lot of the funding and support that has over a long period of time fueled extremism inside Iraq has flowed into Iraq from its neighbors," said the aide, briefing reporters aboard the secretary's plane en route to a refueling stop in Ireland.

"And that does not mean that it's the result of an official government policy in many, if not most, cases. But it does mean that some of these governments can do more to stop some of that facilitation."

U.S. officials said ISIS maintains an elaborate network of illegal operations, from kidnapping and extortion schemes across large swaths of Syria and Iraq to the profitable resale of oil and other assets the group has looted in its march towards Baghdad.

"This is, in addition to being a highly capable and sophisticated terrorist organization," the aide to Kerry said, "essentially a criminal syndicate that is able to sustain some of its operations in that way."

Kerry's aides also said American and Iraqi officials are still hammering out a legal agreement under which the roughly 500 U.S. service personnel that President Obama has announced he is dispatching to Iraq can freely operate.