Prime Minister Fumio Kishida will not accompany U.S. Ambassador to Japan Rahm Emanuel on a trip to Hiroshima this weekend as he needs to focus on the Ukraine crisis, a government source said Wednesday.

During his meeting with Kishida on Feb. 4, Emanuel said he wanted to visit Hiroshima at an early date to offer prayers and flowers to those who suffered from the 1945 U.S. bombing of the city.

Kishida had been eager to join the ambassador's visit, arranged for Saturday. The prime minister represents a constituency in Hiroshima.

Emanuel was once a top aide to former U.S. President Barack Obama, who went to Hiroshima during his presidency in 2016. Kishida, then foreign minister, played an active role in realizing Obama's visit to the city, the first by sitting U.S. president.

Kishida said Wednesday that Japan will impose a set of economic sanctions against Russia and two pro-Russian separatist regions in eastern Ukraine after Moscow formally recognized the areas and ordered the deployment of troops there.

He also said Japan would take additional steps swiftly in coordination with the Group of Seven major developed countries if the crisis deepens.