Key U.N. Security Council members neared agreement late Thursday on a U.N. resolution that would impose sanctions on North Korea for its claimed nuclear test.

The United States reported significant progress in bridging differences with Russia and China, which had sought to moderate the tough sanctions proposed in the U.S. draft resolution.

The upbeat message came after more than two hours of closed-door negotiations among ambassadors from the five permanent council nations – the U.S., Russia, China, Britain and France – and Japan’s ambassador who is the current council president.

The U.S. said it hoped a vote could be held today, though close ally Japan said Saturday was more likely.

“We have made very substantial progress,” U.S. Ambassador John Bolton told reporters after the meeting. “I don’t want to say we’ve reached agreement yet, but many, many of the significant differences have been closed, very much to our satisfaction.”

A new draft of the resolution was sent to capitals Thursday night so ministers can examine the latest changes. Bolton said the full Security Council is meeting this morning.

In the latest version, the United States dropped the idea of a weapons embargo against North Korea and made clear that it was seeking only nonmilitary sanctions to punish the isolated country for exploding a nuclear device in defiance of international warnings.

A North Korean soldier reacts to a photographer on a passing boat Thursday in the North Korean town of Sinuiju, opposite the Chinese border city of Dandong. The U.S. on Thursday began pushing for a U.N. resolution that adds a travel ban on North Korea, while South Korea said it detected no abnormal levels of radioactivity after the North's claimed nuclear test.

China’s U.N. Ambassador Wang Guangya agreed that “good progress has been made” in improving the text. Russia’s U.N. Ambassador Vitaly Churkin said there had been “a number of improvements” and, importantly, council unity “is in good shape.”

“We should act with a cool head and moderation and also do everything to achieve a political, diplomatic outcome of this problem – and this is the spirit we had in those discussions,” Churkin said. “It’s not assured we’re going to get there, but the mood is good and the effort is good, too.”

North Korea warned it would have a firm response to sanctions, Japan’s Kyodo News Agency reported from Pyongyang.

“We will take strong countermeasures,” Kyodo quoted Song Il Ho, North Korea’s ambassador in charge of diplomatic normalization talks with Japan, as saying.

The U.S. draft calls the situation in North Korea, in particular the test the government claimed, “a clear threat to international peace and security” and authorizes sanctions under Chapter 7 of the U.N. Charter.

China opposes any mention of Chapter 7, which allows punishments ranging from breaking diplomatic ties and imposing economic sanctions to naval blockades and military action.

But Wang reiterated Thursday that sanctions should be limited to the non-military measures authorized under Article 41 – which is part of Chapter 7. They include economic penalties, breaking diplomatic relations or banning air travel.

A previous U.S. draft called on all states to undertake and facilitate inspection of cargo to and from North Korea to ensure compliance with sanctions. The new draft would allow states to inspect cargo “as necessary.”

The latest U.S. proposal also drops a call to freeze assets from other “illicit activities such as those related to counterfeiting, money-laundering or narcotics.”

“We’re almost there,” said Japan’s U.N. Ambassador Kenzo Oshima.