World leaders have welcomed the US presidency of Joe Biden, expressing hope for a reset in relations after four turbulent years under Donald Trump.
Prime ministers, presidents and spiritual leaders congratulated Mr Biden after he was sworn in as president on Wednesday.
Many said they looked forward to working with Mr Biden on climate change and Covid-19, among other issues.
This is what some of them said.
UK Prime Minister Boris Johnson
"I look forward to working with him [Biden], and with his new administration, strengthening the partnership between our countries and working on our shared priorities: from tackling climate change, building back better from the pandemic and strengthening our transatlantic security."
Canadian Prime Minister Justin Trudeau
"Canada and the United States will continue this partnership as we fight the global Covid-19 pandemic and support a sustainable economic recovery that will build back better for everyone.
"We will also work together to advance climate action and clean economic growth, promote inclusion and diversity, and create good middle-class jobs and opportunities for our people while contributing to democracy, peace, and security at home and around the world."
European Commission President Ursula von der Leyen
"The United States is back. And Europe stands ready. To reconnect with an old and trusted partner, to breathe new life into our cherished alliance. I look forward to working together with Joe Biden."
Chinese ambassador to the US, Cui Tiankai
"China looks forward to working with the new administration to promote sound and steady development of China-US relations and jointly address global challenges in public health, climate change and growth."
German President Frank-Walter Steinmeier
"Today is a good day for democracy. In the United States of America, it has faced tremendous challenges - and endured. Despite the attempts to tear at America's institutional fabric, election workers and governors, the judiciary and Congress, have proven strong.
"I am greatly relieved that, today, Joe Biden is being sworn in as president and will be moving into the White House. I know many people in Germany share this feeling."
French President Emmanuel Macron
"Best wishes on this most significant day for the American people! We are together. We will be stronger to face the challenges of our time. Stronger to build our future. Stronger to protect our planet. Welcome back to the Paris Agreement!"
Russian Ambassador to the US, Anatoly Antonov
"I just returned from the inauguration, listened attentively to Biden's speech, naturally looked for something in relation to foreign policy, primarily Russia.
"I would like to believe that a new chapter in the development of the United States of America begins today and, of course, that a new chapter in the development of Russian-American relations begins as well. At least, we have repeatedly spoken about this."
Italian Prime Minister Giuseppe Conte
"We are looking forward to the Biden presidency, with which we will start working immediately in view of our presidency of the G20. We have a strong common agenda, ranging from the effective multilateralism that we both want to see, to climate change, green and digital transition and social inclusion."
South Korean President Moon Jae-in
"Joe Biden, congratulations on your inauguration. America is back. America's new beginning will make democracy even greater. Together with the Korean people, I stand by your journey toward 'America United'."
Japanese Prime Minister Yoshihide Suga
"Congratulations to President Joe Biden and Vice-President Kamala Harris on your inauguration. Japan and the United States are allies tied firmly by bonds and shared universal values. I look forward to working with you and your team to reinforce our alliance and to realise a free and open Indo-Pacific."
Taiwanese President Tsai Ing-wen
"President Tsai wishes the new Biden administration smooth policy implementation, and looks forward to building on the strong foundation of the Taiwan-US partnership to further our bilateral collaboration, as well as the prosperity of, and friendship between, the people of both countries."
Indian Prime Minister Narendra Modi
"The India-US partnership is based on shared values. We have a substantial and multifaceted bilateral agenda, growing economic engagement and vibrant people to people linkages.
"Committed to working with President Joe Biden to take the India-US partnership to even greater heights. Congratulations to Kamala Harris on being sworn-in as VP. It is a historic occasion. Looking forward to interacting with her to make India-US relations more robust."
Irish Prime Minister Micheál Martin
"As he takes the oath-of-office, I know that President Biden will feel the weight of history - the presence of his Irish ancestors who left Mayo and Louth in famine times in search of life and hope.
"I hope he will also be conscious of the great pride we in Ireland take in his immense achievement. He is one of us, part of our global family."
Australian Prime Minister Scott Morrison
"Australia and the United States are the best of mates and the best of allies… And this relationship is even more important today than ever before, certainly at any time since the end of the Second World War.
"There's a lot of work for us together, whether it's on climate, on energy, on international security, and importantly, regional security here in the Indo-Pacific and the great partnerships we have with the South Pacific nations, with the South East Asian nations, in Asean."
New Zealand Prime Minister Jacinda Ardern
"We have a common investment in the international rules-based order and I welcome President Biden's intentions for the US to re-join the Paris Agreement and halt its withdrawal from the World Health Organization.
"President Biden's message of unity as he takes office is one that resonates with New Zealanders and, on behalf of New Zealand, I wish him well as he begins his presidency."
Israeli Prime Minister Benjamin Netanyahu
"Congratulations President Joe Biden and Vice-President Kamala Harris on your historic inauguration. President Biden, you and I have had a warm personal friendship going back many decades.
"I look forward to working with you to further strengthen the US-Israel alliance, to continue expanding peace between Israel and the Arab world, and to confront common challenges, chief among them the threat posed by Iran."
Iranian President Hassan Rouhani
"A tyrant's era came to an end and today is the final day of his ominous reign. We expect the Biden administration to return to law and to commitments, and try in the next four years, if they can, to remove the stains of the past four years."
"Under your leadership, may the American people continue to draw strength from the lofty political, ethical and religious values that have inspired the nation since its founding.
"I likewise ask God, the source of all wisdom and truth, to guide your efforts to foster understanding, reconciliation and peace within the United States and among the nations of the world in order to advance the universal common good."
Tibetan spiritual leader, the Dalai Lama
"As someone deeply concerned with the ecological crisis our planet faces, I am so pleased that you are elevating the issue of climate change to your highest priority and that the United States is re-joining the Paris Climate Accord. Global warming is an urgent threat to the whole world and to the survival of our species.
"May I also commend you for other measures you are taking towards the betterment of the United States of America."