Iran has reportedly deployed around a dozen mines in the Strait of Hormuz.

Axar.az reports, citing Reuters, the move is expected to complicate efforts to reopen the narrow waterway, a vital route for transporting oil and liquefied natural gas (LNG).

Exports through the strait, which runs along Iran’s coast, have effectively been halted by the war launched 12 days ago by the United States and Israel, contributing to a surge in global energy prices.

Iran has long threatened to mine the strait in retaliation against any military attacks. Normally, about 20% of the world’s oil and LNG passes through the channel, giving Tehran significant leverage over the U.S. and its allies.

The U.S. military said it targeted 16 Iranian mine-laying vessels on Tuesday.