An international naval coalition said Monday it will step up its presence near a strategic shipping lane off Yemen as it warned of risks for boats transiting through the area.
The Bab el-Mandab Strait, which connects the Red Sea to the Gulf of Aden, is a key passage for world trade.
"Recent attacks against merchant shipping in the Gulf of Aden and Bab el-Mandab have highlighted that there are still risks associated with transits through these waters," the Combined Maritime Forces said in a statement.
A small boat exploded late last month "for an unknown reason" in a thwarted attack on a tanker in the area, the statement said.
"In response to these threats, the Combined Maritime Forces will be increasing the naval presence" in the western part of the Gulf of Aden, said the coalition.
The Combined Maritime Forces is a 31-state naval partnership, based in Bahrain and led by the US, that oversees security in some international waters including the Gulf of Aden.
Yemen is locked in a war between government forces backed by a Saudi-led alliance and Iran-supported rebels, who control much of the country's Red Sea coastline.
Earlier this month, an oil tanker came under fire off Yemen while passing through the Bab al-Mandab strait into the Red Sea, according to the Saudi-led alliance.
In March, the United States warned Yemen's Huthi rebels posed a threat to free movement into and out of the Red Sea.