Use of vessels at least 25 years old

during a period in which vessels may be requisitioned under chapter 563 of this title; or except as otherwise provided in this subtitle, on trade routes serving only the foreign trade of the United States. 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— (Source: (Pub. L. 109–304, § 8(c), Oct. 6, 2006, 120 Stat. 1664.))