At least four oil tankers have diverted course from the Red Sea since overnight strikes by the U.S. and Britain on Houthi targets in Yemen, shipping data from LSEG and Kpler showed.

The attacks were carried out from the air and sea in response to the Iranian-backed Houthi militia’s attacks on ships in the Red Sea, in what is becoming a regional escalation of the Israel-Hamas war in Gaza.

The tankers Toya, Diyyinah-I, Stolt Zulu and Navig8 Pride LHJ were all seen turning around mid-voyage in order to avoid the Red Sea between 0300 and 0730 GMT on Friday, according to ship tracking from the two companies.

One of the tankers, Toya, a very large crude carrier capable of carrying up to 2 million barrels of oil, was unladen, the data showed. The other three vessels are fuel tankers.

Oil prices were up over $3 a barrel, or more than 4%, by 1144 GMT, with Brent trading above $80, amid heightened geopolitical risks.

Meanwhile, Danish oil tanker group Torm TRMDa.CO said on Friday it decided to pause all transits through the southern Red Sea.

Major container shipping companies Maersk MAERSKb.CO and Hapag Lloyd HLAG.DE welcomed measures to secure the region. But they stopped short of saying whether the U.S. and British strikes would be enough for them to return to the Suez Canal, the fastest route between Asia and Europe which accounts for about 12% of global container traffic.

Source: Reuters reported by Ahmad Ghaddar, Robert Harvey and Jonathan Saul and edited by Mark Heinrich