The U.S. military aims to complete the redeployment to Guam of marine elements now in Okinawa by 2020, according to recent congressional testimony by Adm. Samuel Locklear, commander of the U.S. Pacific Command, and other sources.

It is the first time the U.S. forces have revealed a specific target year for the long-delayed marine transfer from Okinawa to Guam.

In a bilateral accord reached in 2011, Japan and the U.S. pledged to complete the transfer as soon as possible after 2014.

But it is unclear whether the transfer will be implemented as planned amid defense budget constraints in the United States and other factors.

A U.S. government source said Thursday it could be completed even in 2017 or 2018, depending on progress in the infrastructure projects on Guam.

In a recent hearing at a House of Representatives committee, Locklear indicated the transfer of Okinawa marines to Hawaii will likely be completed by 2025 or 2026. That means all of the planned relocation of marines from Okinawa to the two U.S. destinations will be completed by 2025 at the earliest.