Highlights: Obama-Medvedev summit in Russia

The following are comments from U.S. President Barack Obama and Kremlin chief Dmitry Medvedev at a summit in Moscow.

ON NUCLEAR NON-PROLIFERATION

Medvedev:

"The non-proliferation issue is the most important for our states. We are bearing the responsibility. Unfortunately the situation in the world is not changing for the better."

"There are regions where the presence of nuclear weapons may create colossal problems and in these areas we should most closely work with our partners."

ON AFGHANISTAN

Obama:

"Second, we have taken important steps forward to strengthen our security through greater cooperation."

"President Medvedev and I have agreeed on the need to combat the threat of violent extremism, particularly from Al-Qaeda."

"This (today's agreement) is a substantial contribution by Russia to an international effort. It will save the United States time and resources for giving our troops the support they need."

ON IRAN

Obama:

"Iran also poses a serious challenge, due to its failure to live up to international obligations."

"This is not just a problem for the United States but raises the prospect of a nuclear arms race in the Middle East which would endanger global security, while Iran's ballistic missile programme could pose a threat to the entire region."

"That's why I'm pleased that we've agreed on a joint statement on cooperation."

ON NORTH KOREA

Obama:

"North Korea has abandoned its own commitments and violated international law and that's why I'm pleased Russia has joined us in the UN security council resolution that calls for strong steps."

ON MISSILE DEFENCE

Medvedev:

"We have agreed that defensive and offensive weapons should be viewed as a whole ... We made a joint statement on missile defence although we have differences on a range of positions."

ON NUCLEAR ARMS TREATY

Obama:

"This legally binding treaty will be completed by the end of this year."

AT OPENING OF TALKS Obama:

"We are confident that we can continue to build on the excellent discussions that we had in London. And that on a whole host of issues -- including security issues, economic issues, energy issues, environmental issues -- that the United States and Russia have more in common than they have differences and that if we work hard in these next few days we can make extraordinary progress that would benefit the people of both countries."

Medvedev:

"We hope that as a result of our conversations today and tomorrow, our fully fledged bilateral contacts, that we will close a number of difficult pages in Russian-American relations and turn a new page." "Even the weather favours our discourse today as it is cold outside."

Obama: "We might as well be inside today."