TOYAKO, Japan (AP) — President Bush on Sunday defended removing North Korea from the list of state sponsors of terrorism and attending the opening ceremonies of the Beijing Olympics as world leaders assembled to address soaring gas prices, climate change and African aid.

They faced major differences, especially over how far to go in trying to set limits on pollutants that contribute to global warming.

The host of this year’s Group of Eight summit, Japanese Prime Minister Yasuo Fukuda, and other leaders would like to see the top industrialized nations and other fast-growing economies such as China and India pledge a 50 percent cut by 2050 in the emissions that contribute to global warming. The Bush administration has not shown any enthusiasm for such a commitment without cooperation from the Chinese and Indians.

“I’ve always advocated that there needs to be a common understanding and that starts with a goal. And I also am realistic enough to tell you that if China and India don’t share that same aspiration, that we’re not going to solve the problem,” Bush said at a pre-summit news conference with Fukuda.

The leaders of the U.S., Japan, Britain, Germany, France, Italy, Canada and Russia planned to kick off the meeting Monday at a remote mountaintop resort overlooking a lake formed by a volcanic crater on the northern Japanese island of Hokkaido. The session ends Wednesday with a larger gathering that brings in eight additional countries — Australia, Brazil, China, India, Indonesia, Mexico, South Korea and South Africa.

Hundreds of protesters rallied under heavy police security Sunday. A demonstration by about 2,500 people on Saturday led to a brief clash with police; four people, including a television cameraman, were detained. Protesters have not been able to get near the summit venue, but have scheduled daily rallies about 60 miles north, in Sapporo, the largest nearby city.

Before the G-8 talks, Bush planned to meet with Russia’s new president, Dmitry Medvedev, who took office last month as ex-President Vladimir Putin’s hand-picked successor. Putin still wields enormous influence at home as prime minister.

White House aides said Bush hoped to bring up areas were the countries could cooperate more, including missile defense and Russia’s bid to join the World Trade Organization.

Medvedev’s appearance could help him make the case he is emerging from Putin’s shadow and carving out a leadership role. In an interview with journalists from G-8 countries last week, Medvedev suggested that he, not Putin, is in charge.

Republican presidential candidate John McCain has urged stripping Russia of its G-8 membership because of autocratic steps by Putin. Neither fellow Republican Bush nor Democratic presidential contender Barack Obama shares that view.

Ahead of the Bush-Medvedev meeting, the Kremlin issued a statement suggesting that good personal ties are developing between Bush and the new president and that a transition period following the change of presidents in Russia “was practically unneeded.” The statement, by the Kremlin press service, mentions that Bush will be replaced next January, but that in the meantime “we have a lot of work on the current agenda with the Bush administration...”

“The overall balance of the Russian-American strategic dialogue remains positive, but that of course does not mean there are no ‘serious differences,’ said the statement. For instance, on missile defense, the Kremlin said, “our basic approaches still differ.”

At a news conference with Fukuda, Bush defended his decision to attend the Olympics opening ceremonies Aug. 8. Among the leaders who plan to skip that event are British Minister Gordon Brown, German Chancellor Angela Merkel and Canadian Prime Minister Stephen Harper. French President Nicolas Sarkozy is considering not attending.

China’s role as host has focused attention on its human rights record and the security crackdown in Tibet; some U.S. conservatives have criticized Bush for planning to go to the opening ceremonies.

“The Chinese people are watching very carefully about the decisions by world leaders and I happen to believe that not going to the opening ceremony for the games would be an affront to the Chinese people, which may make it more difficult to be able to speak frankly with the Chinese leadership,” the president said.