An obsolete vessel acquired under this chapter that is or becomes at least 25 years old may not be used for commercial operation. However, the vessel may be used—
(1) during a period in which vessels may be requisitioned under chapter 563 of this title; or
(2) except as otherwise provided in this subtitle, on trade routes serving only the foreign trade of the United States.
(Pub. L. 109–304, § 8(c), Oct. 6, 2006, 120 Stat. 1664.)