China’s top general Fang Fenghui said on Monday that a fourth North Korean nuclear weapons test is feasible, and that talks are underway between Pyongyang and other regional parties.

Since North Korea recently renounced the 1953 Armistice Agreement with South Korea and shut down its Kaesong factories, a joint-industrial complex employing both South and North Korean workers, the United States has been on its toes trying to ensure stabilization in Asia. But, unfortunately, a diplomatic plea to North Korea to stop its nuclear weapons program is not going to cut it.

China, North Korea’s most important ally, is the main player in easing tensions in East Asia. It is a 9.6 million square kilometer-buffer between North Korea and the United States. Yet, despite its tremendous influence over North Korea, China’s reaction to its neighbor’s threats has been relatively relaxed.

When Secretary of State John Kerry visited Beijing, he urged China to put more pressure on North Korea. All Beijing has done is sign tougher U.N. sanctions — a move that sends a message to North Korea but only hurts the poor and does not affect the people in power. North Korean leader Kim Jong-un remains untested, and it’s time his provocations are met with more than just a slap on the wrist.

Throughout history, China has been the largest support system for the North Korean regime. North Korea would be committing political suicide if it made decisions that would encourage China to cut them off from its economy.

In addition, China has not only one of the world’s largest nuclear arsenals but also the world’s largest military, so there should be no question among North Korean leaders about the devastating consequences of losing China’s support.

Yet here we are. North Korea threatens another nuclear test, and Fang still refuses to state whether China will adopt tougher measures against North Korea in order to mitigate hostility across the Pacific. South Korea and Japan are considering upping their defense, and the United States and South Korea have already organized joint military exercises in the region, with the United States sending B-2 stealth bombers and F-22 fighter jets to send a message to North Korea. The United States is even trying to deter North Korea from obtaining the $4 billion stored overseas by Kim Jong-un’s father, Kim Jong-il.

Diplomacy is always Plan A, but alarming instability in East Asia and strong North Korean resistance pose a unique situation for the United States. Military intervention is always on the table, but after fighting two wars over two decades, there is no appetite for more debt, death and destruction. This is why we need China.

China needs to take a hard-lined, militaristic stance against North Korean aggression. Without a tougher effort from Beijing, North Korea will continue to undercut the international community, and the United States may be forced to move on to Plan B.

A version of this article was published in the Wednesday, April 24 print edition. Raquel Woodruff is a deputy opinion editor. Email her at [email protected].