A Ukrainian official has said Mr. Zelensky’s government did not learn of the funding delay until about a month later. The White House has said the review merely sought to ensure the money was properly spent.

But the freeze irritated diplomats who questioned whether it was tied to Mr. Trump’s demands for Ukraine to investigate two politically fraught allegations: a widely debunked conspiracy theory about election tampering in 2016 and corruption at an energy company that employed the younger son of former Vice President Joseph R. Biden Jr. There is no evidence that the Bidens were involved in wrongdoing.

Once the decision to freeze the aid became public in late August, a bipartisan group of lawmakers pressed the administration to reverse course, saying that holding up the money sent the wrong signal as a new Ukrainian government confronted a continuing military threat from Russia.

William B. Taylor Jr., the top American envoy in Kiev, wrote in a Sept. 9 text message that it was “crazy to withhold security assistance for help with a political campaign.” In response, Gordon D. Sondland, the United States ambassador to the European Union, wrote that “the President has been crystal clear: no quid pro quo’s of any kind.”

Mr. Sondland then suggested that the conversation continue by telephone, rather than by text. On Tuesday, the Trump administration blocked Mr. Sondland from testifying to the House in the impeachment inquiry.

Officials were informed that the freeze had been reversed — and the $141 million in foreign military financing would be released — in a Sept. 12 email from the White House that was then sent around the State Department.

“Apparently, and I don’t have full visibility, decision made last night,” Mr. Kulikowski wrote.

Mr. Freden said the Ukrainian government had already been told that the funds were forthcoming. But he urged State Department employees not to announce the reversal.