Russian President Vladimir Putin is waiting for official results from the U.S. presidential election before congratulating the winner, a Kremlin spokesperson said.

Russian presidential spokesman Dmitry Peskov told reporters on Monday that while the Kremlin hopes “to build dialogue with the next U.S. president” and seek ways to boost bilateral relations, Putin will wait to congratulate the president-elect after legal challenges are settled and the election results become official.

“Anticipating your possible question about congratulations from [Russian President Vladimir] Putin to the U.S. president-elect, I want to say the following: we consider it correct to wait for the official results of the elections to be announced,” Peskov said, according to Russian news agency Tass.

Asked about why Putin was choosing to wait while he was quick to congratulate Trump on his 2016 victory, Peskov said no legal challenges were mounted to the election result four years ago.

“There [in the United States] they are facing certain legal procedures that were announced by the incumbent president, which makes this situation different. So we deem it as correct to wait for the official announcement,” Peskov said.

While some world leaders have been quick to congratulate former Vice President Joe Biden when he was declared on Saturday as president-elect after projected victories in Pennsylvania and Nevada put him over the 270 electoral vote threshold, others have been more reticent. European allies who clashed with Trump over defense and trade issues, notably Germany and France, were among the first to congratulate Biden. Conservative leaders in Hungary and Slovenia, who have been vocal in the past in their support for Trump, have not.

Poland’s head of state and Trump ally Andrzej Duda congratulated Biden on his “successful presidential campaign” following Saturday’s media calls, but not explicitly on his victory. Presidential spokesperson Blazej Spychalski on Sunday clarified Duda’s statement, saying that congratulations to whoever ultimately prevails in the election will be due after electors have cast their votes and the U.S. presidency is officially called.

Mexico’s President Andrés Manuel López Obrador said on Saturday he would wait to congratulate the victor after legal challenges are settled.

Following media declarations of a Biden win, President Donald Trump alleged voter fraud and said any claims of victory are premature, with his campaign announcing a raft of legal challenges.

“The simple fact is this election is far from over,” Trump said in a statement. “Joe Biden has not been certified as the winner of any states, let alone any of the highly contested states headed for mandatory recounts, or states where our campaign has valid and legitimate legal challenges that could determine the ultimate victor.”

“Legal votes decide who is president, not the news media,” Trump added.

Biden has claimed victory in the presidential race, changing his Twitter handle to read “president-elect,” while many media outlets have begun referring to him as such. His declaration prompted pushback from Trump, who said in a statement: “We all know why Joe Biden is rushing to falsely pose as the winner, and why his media allies are trying so hard to help him: They don’t want the truth to be exposed.”

“The American people are entitled to an honest election: That means counting all legal ballots, and not counting any illegal ballots. This is the only way to ensure the public has full confidence in our election,” Trump said.