ConocoPhillips Chairman and Chief Executive Officer Ryan Lance said he decided not to attend a conference in St. Petersburg following talks with the U.S. State Department.

Company officials were advised by the State Department not to go to the May 22 event as the annexation of Crimea by Russia led to diplomatic tensions, Lance, who was planning to attend, told reporters today at the company’s annual meeting in Houston.

The U.S., which is leading global efforts to force Russian President Vladimir Putin to change his actions, has blocked 45 individuals, including OAO Rosneft Chief Executive Officer Igor Sechin, a Putin associate, and 19 entities, including SMP Bank and Bank Rossiya.

Citigroup Inc. Chief Executive Officer Michael Corbat was also among U.S. executives who withdrew from the economic forum scheduled from May 22 to May 24.