Classified briefings for lawmakers from top officials are not unusual and are held on a regular basis on Capitol Hill. But in this case, President Donald Trump belatedly proposed that a planned briefing on North Korea be hosted at the White House, with the secretaries of State, Defense, the U.S. military’s top officer and the head of national intelligence due to speak to senators.

The last-minute decision, coinciding with tough rhetoric from the White House and bellicose threats from North Korea, took lawmakers by surprise and fueled doubts about the Trump administration’s often disjointed efforts at crafting a policy to neutralize the North Korean nuclear threat. Administration officials have publicly jettisoned long-standing U.S. policy on North Korea but have yet to articulate what will replace it.

In a meeting with U.N. Security Council representatives on Monday at the White House, Trump cited the urgency of the threat posed by North Korea’s nuclear and missile programs, and suggested his administration was determined to address the danger once and for all.

“People have put blindfolds on for decades, and now it’s time to solve the problem,” Trump told the diplomats.

The White House has repeatedly said that it has abandoned the Obama administration’s approach of so-called “strategic patience,” saying it will not tolerate North Korea’s march toward a nuclear-armed intercontinental ballistic missile. But it’s not clear how Trump and his deputies intend to crack a problem that has vexed the United States and its allies for more than a quarter of a century.

Senior officials say the primary focus of U.S. policy at the moment centers on a diplomatic push to persuade China to use its influence with North Korea to force Pyongyang back from the brink.

But it’s doubtful Washington has sufficient leverage to convince Beijing to impose an economic squeeze on the North. Moreover, China has always feared any action that could trigger the collapse of the Pyongyang regime on its border. Previous U.S. administrations have tried the same approach and come away disappointed with China’s cautious steps.

“All sides understand the stakes and understand what needs to happen,” a White House official told Foreign Policy, referring to discussions with China. But the official, who spoke on condition of anonymity, said it remained to be seen if China would take the necessary steps against North Korea. He added that “there is not infinite patience on our side” but did not elaborate.

Some experts have urged the White House to impose sanctions directly on Chinese companies if Beijing refuses to press Pyongyang, but administration officials declined to say if that option is under serious consideration.

Experts told the Senate Armed Services Committee at a hearing on Tuesday that even if China agreed to  ramp up pressure on the regime, North Korea probably would not give up its efforts to build nuclear warheads for long-range ballistic missiles.

“We essentially have to prepare for a North Korean capability that will ultimately reach the United States,” said Victor Cha of the Center for Strategic and International Studies, who served in the former Bush administration.

Cha said efforts at deterring the North through sanctions or military deployments are worth pursuing but also posed dangers “because of the unpredictability of this regime.”

The Trump administration has warned that all options are on the table, including potential military action. But a former senior official in the Bush White House said that destroying North Korea’s nuclear arsenal through military strikes could prove impossible, given the technical advances made by the regime.

There are an increasing number of nuclear targets and those targets are increasingly hard to reach, said Aaron Friedberg, a professor at Princeton University who served under former Vice President Dick Cheney.

“North Koreans are starting to develop mobile ballistic missiles. The problem with preempting or attacking in a preventative way and destroying the North Korean nuclear capabilities is only getting worse,” Friedberg told the committee.

The sense of urgency over North Korea’s nuclear program has steadily mounted in the U.S. intelligence community and the Pentagon over the past decade, as the regime has demonstrated increasing technical prowess.

Although the North makes plenty of false claims about its nuclear capabilities, “the nuclear tests are not solely provocations or opportunities for saber rattling,” said Kelsey Davenport of the Arms Control Association. Over the past five tests, the country has increased the explosive yield of its nuclear warheads, and the regime’s scientists are also likely using the tests to experiment with different warhead designs.

“After five tests we should also assume that North Korea can build a warhead small enough to fit on short or medium range ballistic missiles,” Davenport said.

It’s unlikely that Wednesday’s briefing at the White House will clear up concerns among many lawmakers about the administration’s handling of tensions on the Korean peninsula, particularly after its bungled messaging about the location of an aircraft carrier.

The administration suffered an embarrassing episode last week when it acknowledged that a naval strike group, spearheaded by the USS Carl Vinson aircraft carrier, was not off the coast of the Korean peninsula as officials had announced earlier. In fact, the warships were thousands of miles away, training with the Australian navy.

The incident reinforced fears in Japan and South Korea about U.S. credibility and that the Trump administration was failing to consult with allies about its responses to North Korea. One South Korean presidential candidate, Hong Joon-pyo, from the conservative party of ex-president Park Geun-hye, said the confusion caused by the American administration’s statements on the whereabouts of the carrier could mean that Seoul would “not trust” Trump’s words in the future.

Still, administration officials believe an assertive U.S. military presence in the region in recent weeks has sent an unmistakably stern warning to North Korea as the regime appears poised to conduct its sixth nuclear test.

The United States is set to test one of its own missile systems on Wednesday, when an unarmed  Minuteman III ballistic missile will be launched from Vandenberg Air Force Base in California.

“These Minuteman launches are essential to verify the status of our national nuclear force and to demonstrate our national nuclear capabilities,” Col. John Moss, commander of the U.S. Air Force’s 30th Space Wing commander, said in a statement.

Off the coast of Korea and Japan this week, U.S. Navy ships are also conducting drills in the Sea of Japan with the South Korean and Japanese navies. The destroyers USS Wayne E. Meyer and Wang Geon are engaged in one exercise, while two other destroyers — the USS Fitzgerald and Japan’s Chokai — are also operating together nearby.

Pyongyang greeted the deployments with typical bombast, after the USS Carl Vinson eventually made its way toward the Korean peninsula, and the USS Michigan, a guided-missile submarine, made a port visit to South Korea this week.

“If the enemies dare opt for the military adventure despite our repeated warnings, our armed forces will wipe the strongholds of aggression off the surface of the earth through powerful preemptive nuclear attacks,” Defense Minister Pak Yong Sik said in a televised speech Tuesday.

The regime kicked off Tuesday with a vast live-fire artillery exercise that included as many as 400 long-range guns — the same weapons that would be trained on Seoul’s civilian population in the event of a war.