The passage of US warships through the Straits also raised controversy, as the convention forbids the transit of non-Black Sea nations' warships with guns of a
calibre larger than eight inches (203 mm). In the 1960s, the US sent warships carrying 305 mm calibre
ASROC missiles through the Straits, prompting Soviet protests. The Turkish government rejected the Soviet complaints, pointing out that guided missiles were not guns and that such weapons had not even existed at the time of the Convention's agreement so were not restricted.
[25]
In April 1982, the Convention was amended to allow Turkey to close the Straits at its discretion in peacetime as well as during wartime.[26][
verification needed]
The
United Nations Convention on the Law of the Sea (UNCLOS), which entered into force in November 1994, has prompted calls for the Montreux Convention to be revised and adapted to make it compatible with UNCLOS's regime governing straits used for international navigation. However, Turkey's long-standing refusal to sign UNCLOS has meant that Montreux remains in force without further amendments.