Answer questions based solely on the following content, and do not use additional information. Content: There have been various theories regarding the timing of Ukraine's counterattack. Ukrainian Prime Minister NAME_1 stated in early April that Ukraine's counterattack may begin in the summer. He later said that the counterattack would begin "in the near future". According to Newsweek, previously leaked Pentagon documents indicate that Ukraine's attack appears to begin on April 30th. Question: When is the most likely time for Ukraine's counterattack to begin?