Russian President Vladimir Putin had a phone call with US President Donald Trump on Sunday. The Kremlin announced news of the call, and t he White House confirmed it 24 hours later.

It's not clear why the US administration delayed telling the public about the call.

The White House has restricted the number of people who can listen to Trump's calls, and it no longer issues a public summary of every call.

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Russian President Vladimir Putin had a phone call with US President Donald Trump on Sunday, according to a statement published by the Kremlin.

The White House confirmed the call took place 24 hours later.

In the call, Putin thanked Trump for US intelligence that helped Russia arrest two of its citizens Friday who were thought to be planning a terrorist attack in St. Petersburg on New Year's Eve, according to CNN. The outlet also reported that the two world leaders "discussed the need for a new American ambassador in Moscow."

Trump interrupted a two-week vacation in Florida, where he was playing golf, to take the call, CNN said.

It is not clear why the White House let the Kremlin report news of the call first. Such news needs to be cleared and vetted by White House staff, who are in a Christmas quiet period.

The number of people invited to listen in on the president's calls has also been restricted recently, since a whistleblower reported that Trump used a call with the president of Ukraine to request a political favor meant to help aid his reelection in 2020. CNN reported:

"Nobody is allowed on the calls," a White House official said, describing the new effort to limit those with access to the calls to only the president's senior-most aides, barring some senior and mid-level career staff from listening in. "The barn door officially closed after the horse escaped."

"Yesterday, President Vladimir Putin of Russia called President Donald J. Trump to thank him for information the United States provided that helped foil a potential holiday terrorist attack in Russia," the White House said Monday in a statement, according to The Hill.

"Both presidents committed to continuing counterterrorism cooperation between the two countries. The presidents also discussed the state of relations between the United States and Russia and future efforts to support effective arms control."

It used to be standard practice for the White House to release a summary of every call a president had with a world leader. The Trump administration ended the practice in July 2018, and it now releases only some.

In a separate statement, the Kremlin invited Trump to visit Moscow in 2020 to watch a big military parade and to discuss arms control, the Kremlin said.

"Putin noted that Russia and the US were historically responsible for ensuring global security and stability, and that Moscow speaks in favor of normalizing bilateral relations and establishing an equal dialogue based on the mutual respect of interests.

"The president of Russia also reaffirmed his invitation to Donald Trump to visit Moscow to take part in the celebrations of the 75th anniversary of victory in the Great Patriotic War."

The Great Patriotic War is how Russians commonly refer to World War II. Trump has historically expressed enthusiasm for military parades.