Senior Ukrainian officials told The New York Times they were blindsided when they discovered that the U.S. wasn’t releasing military aid this past summer. “It was a total surprise,” Pavlo Klimkin, Ukraine’s foreign minister at the time, told the Times when he learned that the aid was blocked with no explanation. A July 25 phone call between President Donald Trump and Ukrainian President Voldymyr Zelensky in which the two leaders discussed investigating former Vice President Joe Biden’s son has put fresh scrutiny on the decision to put a hold on military support from Washington in early July. Speculation is growing over whether Trump manipulated foreign policy for his own political gain by withholding the security assistance to attempt to tarnish a family member of his potential 2020 rival. Hunter Biden had business dealings in Ukraine while his father, then the vice president, was tapped to oversee American policy toward Ukraine and has never been found to have any wrongdoing in his position.

Editor’s note: New U.S. military assistance for Ukraine was put on hold in early July. A previous version of this report incorrectly indicated it came after the disputed July 25 phone call between Donald Trump and Ukraine President Voldymyr Zelensky.