U.S. Secretary of State Rex Tillerson called on North Korea on Thursday to abandon its nuclear and ballistic missile programs, saying the isolated nation “need not fear” the United States.

Tillerson made that declaration after meeting Japanese Foreign Minister Fumio Kishida in Tokyo, where they discussed possible new approaches in dealing with Pyongyang.

He said 20 years of U.S. diplomatic and other efforts to get North Korea to denuclearize have failed, but gave no specifics about how the Trump administration, which is currently doing a policy review, would tackle the issue. Tillerson described the weapons programs as “dangerous and unlawful.”

The former Exxon Mobil CEO is making his first trip to Asia as the top U.S. diplomat. Tensions are running high on the divided Korean Peninsula, and North Korea last week launched four missiles into seas off Japan and where the U.S. is currently conducting annual military drills with South Korea. Pyongyang views this as a rehearsal for invasion.

“North Korea and its people need not fear the United States or their neighbors in the region who seek only to live in peace with North Korea,” the secretary of state told a news conference in Tokyo. “With this in mind, the United States calls on North Korea to abandon its nuclear and ballistic missile programs and refrain from any further provocation.”

He later met separately with Japanese Prime Minister Shinzo Abe.

In Beijing, a North Korean diplomat said Thursday that Pyongyang must act in self-defense against the U.S.-South Korea military drills, which he said have brought the region to the brink of nuclear war. He said the drills were aimed at using atomic weapons for a pre-emptive strike against North Korea. Washington says the maneuvers are routine and defensive.

“The United States holds a joint military exercise every year to push the situation on the Korean Peninsula to a serious situation, and that is the source of the super tough measures we must take,” Pak Myong Ho told reporters in a rare briefing at the North Korean Embassy in the Chinese capital. He spoke through a translator.

North Korea has accelerated its weapons development in violation of multiple U.N. Security Council resolutions and despite tough sanctions levied against it. Last year, the North conducted two nuclear test explosions and 24 ballistic missile tests. Experts say it could have a nuclear-tipped missile that could reach the United States within a few years.

Citing the continued North Korean missile launches this year, Tillerson said that “in the face of this ever-escalating threat it is clear that a different approach is required.” He said his trip was intended to get input from other governments. Tillerson, who is traveling without the usual contingent of journalists who normally cover the secretary of state, will be in South Korea on Friday and then China on Saturday.

Both Tillerson and Kishida urged China to use its economic leverage with North Korea to push it to change course.

During last year’s election campaign, presidential candidate Donald Trump called into question U.S. security alliances and called for Tokyo and Seoul to contribute more for their defense. Tillerson, however, stressed that cooperation with Japan and South Korea was “critical.”

Kishida said the U.S. and Japan had an “unwavering bond.” In a sign of that, Tillerson reiterated that a U.S.-Japan mutual defense treaty covers Japanese-administered islands in the East China Sea also claimed by China.

Japan and South Korea both host tens of thousands of U.S. troops. Washington has been urging its two allies to step up security cooperation despite their historically strained relations. This week, the three nations’ navies have conducted missile defense information-sharing drills in the region.

Kishida described the trilateral cooperation as “indispensable.” But he said the Japan-South Korea relationship has been strained over failure to implement a 2015 agreement in which Japan’s government consented to compensate South Korean victims of sexual slavery inflicted by the Japanese military during World War II. In return, South Korea was to stop criticizing Japan on the issue.

Earlier this year, Japan withdrew its ambassador from South Korea after activists there erected a statue outside a Japanese consulate to commemorate the wartime victims, known as “comfort women.”

Tillerson said he appreciated how “painful” it was to deal with such historical issues, but urged both sides to carry out the agreement and bring the matter to a rapid conclusion. He said it was important for all three nations to maintain a strong alliance “in which there is no space between us.”

(AP)