North Korea has agreed to reopen the investigation into Japanese citizens it abducted in the 1970s and 1980s. In return, Japan will lift some of the sanctions it has imposed on the North over its nuclear bomb tests and missile launches.

The agreement, reached on Friday, also called for Japan to provide humanitarian aid to the North and the two sides to conduct negotiations for normalizing relations.

It is not undesirable for Japan or any other member of the international community to engage North Korea, one of the most isolated regimes in the world. It is also understandable that the latest accord deals with a humanitarian issue.

But the agreement did not come at an opportune time. The North Korean government remains as hostile as ever toward South Korea and the United States. Most of all, the accord came when the international community, including the North’s only ally China, has been pressuring Pyongyang to renounce its threat to conduct a fourth nuclear bomb test.

Most worrisome is the possibility that the agreement may dent international sanctions that have been in force and cause a crack in the alliance of South Korea, Japan and the U.S. on denuclearizing the North.

Both Tokyo and Pyongyang did not say what sanctions will be lifted first upon the North’s opening of a new investigation into the abduction issue. But they said that the sanctions, which are independent of U.N. sanctions imposed on the North, include restrictions on bilateral human exchanges, limits on how much money ethnic Koreans in Japan can remit or take on visits to North Korea, and a ban on North Korean-flagged ships from visiting Japanese ports.

Japanese officials said they will maintain U.N. sanctions even if Tokyo lifts some of its own sanctions, but experts already raise the possibility that any such action would violate U.N. sanctions. They especially take note of the possibility of money transfers to Japan, which certainly would ease the financial strain the North has been suffering from in the wake of U.N. sanctions.

The agreement between North Korea and Japan may also put the three-nation alliance against the North’s nuclear program into trouble. It was just about two months ago that leaders of the three countries agreed in The Hague, Netherlands, to maintain a joint stance on the issue. Seoul officials said Tokyo informed both South Korea and the U.S. of the agreement only shortly before the official announcement.

Shinzo Abe, the Japanese rightist prime minister, might well have been tempted to achieve a diplomatic breakthrough in order to broaden domestic support for him. He also might have wanted to use his North Korean policy as a leverage in his dealings with Seoul, Washington and China.

Whatever his motives may be, both South Korea and the U.S. must press him to consult related governments before lifting any sanction on the North. He should be reminded again that any issue involving North Korea should be reviewed from the perspective of regional security and global nonproliferation.

The worst scenario would be for the North to be able to slip through some of the U.N. sanctions without doing anything about its nuclear and missile programs.