President Donald Trump expressed frustration at China in tweets following North Korea's launch of "deep strike" missiles into South Korean waters during a show of force Monday.
Following the launch of what has been confirmed to be the North's first successful intercontinental ballistic missile (ICBM), Trump, who has sought to work with China to quash North Korea's nuclear program, suggested China should increase pressure on the North.
Trump has reportedly grown frustrated with Chinese President Xi Jinping's unwillingness to pressure the North. The New York Times has reported Trump has said he's prepared to act unilaterally on the issue.
Trump resumed tweeting Wednesday morning, before leaving for the G-20 summit in Europe, taking aim at China's economic relationship with North Korea.
The United States and South Korea on Tuesday had fired back at North Korea's military provocations, as U.S. Secretary of State Rex Tillerson called the situation a "new escalation of the threat" from the reclusive nation.
The Pentagon warned the country and its leader that the U.S. was "prepared to defend ourselves and our allies and to use the full range of capabilities at our disposal against the growing threat from North Korea."
"The United States seeks only the peaceful denuclearization of the Korean Peninsula," chief Pentagon spokesperson Dana White said in a statement. "Our commitment to the defense of our allies, the Republic of Korea and Japan, in the face of these threats, remains ironclad."
Tillerson added: "As we, along with others, have made clear, we will never accept a nuclear-armed North Korea."
Gen. Vincent Brooks, the top American general in South Korea, warned Wednesday that self-restraint was the only thing preventing war in the region.
"Self-restraint, which is a choice, is all that separates armistice and war," he told The New York Times. "As this alliance missile live-fire shows, we are able to change our choice when so ordered by our alliance national leaders.
"It would be a grave mistake for anyone to believe anything to the contrary."
The U.S. has also requested an emergency meeting of the United Nations Security Council, which is expected to take place on Wednesday.
The North's missile launch, its 11th this year, is the latest in a string of tests as it continues its aim to develop an intercontinental ballistic missile capable of reaching the United States. Monday's launch represents a significant milestone in that venture, and experts say the rocket's trajectory and 37 minute flight time could allow such a weapon to hit the state of Alaska.
North Korean state media claimed the new missile was capable of carrying a large nuclear weapon, but The New York Times notes experts still doubt the country can make warheads small enough to fit onto an ICBM.
The North often conducts major military exercises around important international and American events, and has in the past fired weapons around the American July Fourth holiday. But the move is sure to increase pressure on Trump's administration and any plans to rein in the hermit nation.
Kim used the launch to taunt the United States during its Independence Day holiday, calling the missile a "gift" to Americans.
"We should send them gifts once in a while to help break their boredom," he said, according to the country's state-run news agency.
The president spoke by phone with Xi and Japanese Prime Minister Shinzo Abe over the weekend to discuss North Korea, and the White House said "both leaders reaffirmed their commitment to a denuclearized Korean Peninsula."
This article has been updated with comment from Gen. Vincent Brooks and Trump's tweets Wednesday morning.