Back during WWII, much of the sea traffic was from the Americas to Europe, hardly any trading whatsoever in the Pacific, and more of it going to Japan than anywhere else. Today with China and India consuming more oil, sea lanes throughout the world are as busy as WWII's Atlantic. When you shop at your nearest Walmart, for example, almost all of the merchandise inside is made in China. Trade sea lanes are no longer the same.
Therefore, while the US Navy intends to escort its carrier battle groups, its Marine Expeditionary Forces, and its Urgent Replenishment Ships, it has given up the ghost to convoy merchant vessels. The last of the OHPerrys are not being replaced by frigates, but with littoral combat ships. These ships can provide some ocean escorting, but there are not nearly enough to do the job of NATO ocean escorting. Why bother when Europe's oil supply is being brought from another direction?
Thus, in the future replenishment ships and supply vessels will have to either defend themselves or be risked without naval escorting. Most navies and merchantmen intend to use multitude sea lanes to confound their enemies.
Back during WWII Canada and Britian built hundreds of corvettes, and the US built hundreds of destroyer escorts, frigates, to cross the North Atlantic. None of these had the range to cross the Pacific without a fuel stop. Any ship less than 2,000 tons displacement, a corvette today doesn't have the range to cross the Pacific heavily armed as a frigate.
Some mileage figures:
Range of a few frigates
Anzac class 6,000 nm @ 18 knots
Duke class 7,800 nm @ 15 knots
La Fayettes 9,000 nm @ 12 knots
Formidables4,000 nm @ 18 knots
Floreals 10,000 nm @ 10 knots
Range of a few corvettes
*note I found a few with over 4,000 nm but no clue at what speed, I assume around 10-12 knots
Baynunah class 2,400 nm @ 15 knots
Laksamana class 2,300 nm @ 18 knots
Qahir class 2,000 nm @ 20 knots
Range of a few ocean patrol vessels
River class 7,800 nm @ 12 knots
Otago class 6,000 nm @ 12 knots
