After Johnson resigns, Biden says US-UK 'special relationship' remains 'strong'

In a new statement following the resignation of U.K. Prime Minister Boris Johnson, President Joe Biden on Thursday stressed "the special relationship" between the U.S. and U.K. "remains strong and enduring."

Biden did not mention Johnson by name or his resignation explicitly, but underscored that the U.S. will continue to work with the U.K. government on critical issues, including the war in Ukraine -- an issue Biden and Johnson have worked closely on together.

"The United Kingdom and the United States are the closest of friends and Allies, and the special relationship between our people remains strong and enduring," Biden said in the statement. "I look forward to continuing our close cooperation with the government of the United Kingdom, as well as our Allies and partners around the world, on a range of important priorities. That includes maintaining a strong and united approach to supporting the people of Ukraine as they defend themselves against Putin's brutal war on their democracy, and holding Russia accountable for its actions."

Later Thursday, when departing the Presidential Medal of Freedom ceremony at the White House, Biden was asked by reporters if he had a reaction to Johnson's announcement.

"No, this is part of the process," he responded.

Nevertheless, Johnson's resignation could complicate Biden's goal to strengthen the Western alliance in the face of Russia's aggression in Ukraine.

The two spoke on the issue during a call in April, and "affirmed their commitment to continue providing security and humanitarian assistance to Ukraine in the face of ongoing atrocities by Russia," according to a White House readout of the conversation.

The two leaders then met in June at a summit of G-7 countries, where they both urged nations to remain united against Russia amid its ongoing invasion of Ukraine. The conflict, entering its fifth month, has roiled global energy markets.

In his remarks Thursday announcing his resignation, Johnson cited Britain's support of Ukraine as a top achievement.

"I'm immensely proud of the achievements of this government, from getting Brexit done to settling our relations with the continent for over half a century … and, in the last few months, leading the West in standing up to [Russian President Vladimir] Putin's aggression in Ukraine," he said.

"And let me say now, to the people of Ukraine, that I know that we in the U.K. will continue to back your fight for freedom for as long as it takes," he added.

White House press secretary Karine Jean-Pierre told reporters Thursday that the administration doesn't believe Johnson's resignation will impact Biden's efforts to unite Europe.

"Our alliance with the United Kingdom continues to be strong," Jean-Pierres said. "Our special relationship with the people in the country will continue to endure. None of that changes."

Jean-Pierre also pointed to Biden's recent meeting with NATO leaders in Madrid, where leaders made clear that Russia now poses the "most significant threat to Allied security."

"What you're seeing currently today, because of the leadership of this president, is a more unified NATO. I don't think that changes at all," Jean-Pierre said.

ABC News' Alexandra Hutzler contributed to this report.