People celebrate as President-elect Joe Biden is declared the winner of the presidential election

Washington -- While congratulations have flowed in from around the world for Democrat Joe Biden in his victory over Republican President Donald Trump, some world leaders have been conspicuously quiet.

Russian President Vladimir Putin and Chinese leader Xi Jinping are among the heads of state who still haven’t sent warm wishes to Biden more than a day after he claimed victory and promised a return to a more values-based foreign policy. That silence says as much about the diplomatic challenges facing Biden as it does the unconventional approach of Trump.

Here are some of those who haven’t spoken up so far:

Russia

No foreign leader loomed quite as large over Trump’s time in office as Putin. Trump was persistently dogged by allegations that his successful 2016 campaign for the presidency benefited from the help of Russian intelligence and a state-sponsored disinformation campaign. Trump’s refusal to condemn Putin drove his domestic critics to fury, even as Russia’s geopolitical ambition ran contrary to U.S. strategy from Ukraine in Eastern Europe to Syria and the Middle East. Now, Russia could face a return to a more confrontational U.S. approach under Biden. Opposition leader Alexey Navalny, who’s in Germany recovering from a near-fatal poisoning attack, spoke out on the U.S. election before Putin, saying elections were “a privilege which is not available to all countries.”

China

Xi, who issued a statement congratulating Trump the day of his victory speech in 2016, is likely seeking to avoid the wrath of a U.S. leader who is still contesting the outcome. While English-language state media outlets struck a hopeful tone, strategic rivalry between the two nations is expected to continue under Biden. Chinese government advisers expect the Biden administration to push back against China’s growing assertiveness and team up with allies to confront Beijing over the treatment of Uighurs in Xinjiang and its crackdown on Hong Kong. The U.S. is likely to continue pursuing closer ties with Taiwan, considered the most sensitive bilateral issue between the world’s two largest economies. Xi’s silence contrasted with Taiwanese President Tsai Ing-Wen, who quickly congratulated Biden with a tweet, reflecting that the “values on which we have built our relationship could not be stronger.”

Brazil

The populist leader of Brazil, Jair Bolsonaro, has been referred to as the “Trump of the Tropics” and has previously said he hoped that the U.S. president would get re-elected. At an event on Nov. 7, Bolsonaro made some brief comments on the U.S. and foreign policy, but didn’t comment specifically on Biden’s victory. “We pay attention to foreign policy, we have our preferences, and what happens abroad matters to each one of us here,” he said. “I am not the most important person in Brazil, just as Trump is not the most important person in the world, as he has said himself.”

Mexico

Mexican President Andrés Manuel López Obrador told reporters Saturday that he doesn’t want to be “imprudent” about congratulating Biden. “I want to wait until the electoral process is finished,” he said, even as the peso rose with traders betting Biden would be better for Mexican exports. Despite Trump campaigning on building a wall along the Mexico-U.S. border and blaming the government in Mexico City for the flow of Central American migrants toward the U.S. border, Trump has called his relationship with Lopez Obrador, or AMLO, “incredible,” and the two seem to enjoy friendly ties cemented by the Mexican president’s efforts to stop Central American migration and willingness to renegotiate the North American Free Trade Agreement. AMLO was one of the few leaders to trek to DC in the middle of the pandemic to meet Trump in person, flying commercial to do so.

North Korea

Few world leaders have benefited from Trump more than North Korean leader Kim Jong Un, who’s had three summits with the U.S. President since June 2018 that altered the course of the relationship -- from an exchange of insults to a strange friendship characterized by handshakes and warm letters. Yet North Korea, which for decades has presented some of the most difficult security challenges for the occupant of the White House, is likely to remain silent on the results of the U.S. presidential election. A search through its state media from 1996 shows it’s made no mention about the winner of the vote in the days following an election. That doesn’t mean Pyongyang is ignoring what’s going on. The North Korean regime has a history stretching back decades of timing provocations around U.S. elections to grab maximum attention, according to an analysis by the Centre for Strategic and International Studies’ Beyond Parallel.

Turkey

Turkish President Recep Tayyip Erdogan has benefited enormously from Trump’s unconventional approach to the Middle East, as well as the war in Syria. And so while Turkey on Sunday congratulated the West African nation of Guinea on its election, Erdogan has yet to send his regards to Biden as Trump continues to complain, without evidence, that the election was stolen. Erdogan has so far evaded sanctions for Turkey’s purchase of Russia’s S-400 air defence missile system. He convinced Trump to pull U.S. troops out of Kurdish areas in Northern Syria -- a move that shocked many military observers and allowed Turkey to send its own forces into the zone. “President Erdogan -- He’s tough, but I get along with him,” Trump said in 2019. Biden, who has previously called for the U.S. to support Turkish opposition parties, could end up enforcing sanctions on Erdogan.