The United States called Friday for tougher U.N. sanctions after North Korea said it test-fired its biggest intercontinental ballistic missile to date, with Kim Jong Un vowing to expand his country’s “nuclear war deterrent” while preparing for a “long-standing confrontation” with the United States.

North Korean state media reported the North’s first long-range test since 2017, and South Korea and Japan said they detected it. Thursday’s launch extended a barrage of weapons demonstrations this year that analysts say is aimed at forcing the United States to accept the idea of North Korea as nuclear power and remove crippling sanctions against its broken economy.

At a U.N. Security Council meeting Friday, U.S. Ambassador Linda Thomas-Greenfield said the U.S. would propose a resolution “to update and strengthen” Security Council sanctions. She declined to specify what those new measures might be.

“It is clear that remaining silent, in the hope that the DPRK would similarly show restraint, is a failed strategy,” she said. DPRK is an acronym for the country’s formal name, the Democratic People’s Republic of North Korea.