WASHINGTON (Yonhap) -- U.S. President Barack Obama made clear Monday that North Korea will be able to gain nothing from its provocative strategy.

After summit talks with Japanese Prime Minister Yoshihiko Noda here, Obama emphasized that the old pattern of Pyongyang taking provocative actions and getting concessions from the outside world is finished.

"They will not be able to purchase anything from further provocative acts," Obama said at a press conference.

Obama described the North's recent missile launch and threats of additional provocations as a "sign of weakness, not strength."
He said North Korea was a topic of extensive discussion with the Japanese leader.

"The old pattern of provocation that then gets attention and somehow insists on the world purchasing good behavior from them, that pattern is broken," Obama added.

He warned of stronger sanctions should Pyongyang stay on the course of hostility.

"The more you engage in provocative acts, the more isolated you will become, the stronger sanctions will be in place, the more isolated you will be diplomatically," he said.

Obama said he would not predict what might happen in the coming months amid press reports that the North may be preparing for another nuclear test.

He said the U.S., Japan, South Korea and other nations in the region are unified in insisting that the North abide by international responsibilities and norms.

"There is a great possibility they will conduct a nuclear test," said the Japanese premier, on his first trip to the U.S. since taking office in August. Noda pointed out that the North carried out nuclear tests in 2006 and 2009 after missile launches.

Pyongyang's missile launch on April 12, Noda said, undermined the efforts of regional powers to resolve the North Korea issue through dialogue.