WASHINGTON - President Barack Obama, wrapping up a 47-nation nuclear security summit, said Tuesday he is confident China will join other nations in pressing for tough new sanctions on Iran for continuing to defy the international community in seeking nuclear weapons.

"Words have to mean something. There have to be some consequences," Obama told reporters at a news conference at the conclusion of the two-day gathering.

He was asked about China's reluctance in the past to join other major nations in backing tough sanctions.

Chinese President Hu Jintao on Tuesday gave a speech to the group calling for "effective" measures to safeguard nuclear weapons and materials but stopped short of mentioning Iran's program.

Hu and Obama met for 90 minutes on Monday after which U.S. officials said the two agreed to tell their aides to work on a tough new sanctions program. However, a Chinese spokesman did not mention sanctions in his description of the meeting.

China imports oil from Iran and in the past had been reluctant to endanger that supply line.

"The Chinese are obviously concerned about what harm this might have on the economy generally," Obama said. "Iran is an oil-producing state. ... A lot of countries around the world have trade relationships with Iran and we're mindful of that."

But Obama said Hu had assured him that China would participate in drafting sessions at the United Nations on a new tough sanctions regime.

"I think that we have a strong number of countries on the Security Council who believe this is the right thing to do," Obama said. "But I think these negotiations can be difficult."

China is one of five permanent members of the Security Council with veto powers, along with the U.S., Russia, Britain and France.

Obama said that the new sanctions would make it easier to isolate Iran, as the global community had done for North Korea as it continued to develop nuclear weapons.

Obama said Pyongyang had chosen a path of "severe isolation," which has hurt the North Korean people. Obama said he hoped sanctions would add pressure on North Korea's leaders to return to the six-party talks.

But Obama said he believes the U.S. approach would make it more likely for North Korea to alter its behavior rather than allowing the communist nation to operate its nuclear program without consequences.

"Sanctions," Obama acknowledged, "aren't a magic wand."

"What sanctions do accomplish is hopefully to change the calculus of a country like Iran so that they see that there are more costs and fewer benefits to pursuing a nuclear weapons program," he said.