On Monday, several crucial Japanese oil wholesalers announced that come October the firms will cease importing Iranian oil. The announcement, which comes after increased U.S. pressure and the threat of sanctions on any country doing business with Iran, has already caused oil prices to rise, according to a report from Reuters.

Japan had been in negotiations to secure a waiver which would allow Japanese firms to continue importing Iranian oil after the sanctions hit in November. However, according to Agence France Presse (AFP), the Japanese abandoned the negotiations after it became clear they would not be successful.

As an Island nation, Japan depends heavily on foreign oil, especially from the Middle East. However, according to AFP Iranian crude accounts for just slightly more than 5 percent of Japan’s total imports. By agreeing to abide by U.S. sanctions, Japan will need to look for additional oil sources. What those might be, however, have yet to be disclosed by any of the firms involved.

“We’ve been saying we will observe a government decision (on Iranian oil imports), but we can’t comment further as we don’t disclose information on individual trades,” a spokeswoman for Japanese oil wholesale firm Showa Shell Sekiyu said on Monday while speaking to AFP.