All that is in the distant past. North Korea now claims that it can put hydrogen bombs with adjustable yields atop intercontinental-range ballistic missiles targeted at American territory. North Korea’s transformation from nuclear teetotaler to outright nuclear addict has been frustrating and astounding. But it’s not yet time to panic. Despite provocative photos of a warhead being inserted into an ICBM, North Korea cannot yet hit the United States with nuclear-tipped missiles.

Before that, North Korea will need to iron out range and payload tradeoffs for its long-range missiles, as well as some kinks in reentry vehicle survival observed in the most recent tests. Integrating the warhead with the missile and establishing command and control procedures and technologies will also be necessary and will take time. And how many missiles does North Korea really need to accomplish its goals? No one really knows.

There’s still a lot to worry about. Since it began testing in 2006, North Korea has found a way to substantially increase the yield of its devices. Early estimates peg Sunday’s test anywhere between 50 kilotons and 140 kilotons of TNT, based on a seismic reading of 6.3 on the Richter scale. This is four to six times larger than the 15-25 kiloton test of September 2016. Previous tests had much lower yields, and the first one in 2006 was widely considered to be a failure.

According to North Korea, the latest test was an advanced weapon design—a true two-stage (fission triggering fusion) thermonuclear weapon (a hydrogen bomb) with adjustable yield. There is no way to confirm this claim unless atmospheric sampling detects certain noble gases (for example, xenon) that are associated with the detonation of a thermonuclear device. A breach in the containment of the underground test site could provide helpful data in the next few weeks.

This is not the first time North Korea has claimed it could produce a hydrogen bomb. The regime has an incentive to exaggerate its capabilities to get the United States to back down from supporting South Korea. Absent some quick and effective diplomacy, however, it is only a matter of time before North Korea is able to translate these advances into strategic goals. A more efficient, compact design would reduce the weight and accuracy demands on the long-range ballistic missiles that would carry them. More powerful warheads can take out targets even if the missiles miss their mark.

One has only to look at the damage to Hiroshima and Nagasaki in 1945 to understand that even “small” nuclear weapons wreak unacceptable destruction. Still, the United States has lived with the threat of thousands of Soviet nuclear weapons targeted at cities and military installations for decades. The difference here is in perception: If one believes, as U.S. National Security Advisor H.R. McMaster apparently does, that North Korea cannot be deterred from using such weapons, then any advances that enable North Korea to lob a nuclear-armed missile at the United States are frightening indeed.

There is a good chance that North Korea can in fact be deterred. Kim Jong-un may be brutal, but he seems to be rational. Why would he want to ruin his regime with a nuclear war? There is no indication that he thinks he can win a nuclear war with the United States—he can’t fail to recognize the many thousands of nuclear weapons the United States still has.

That said, putting faith in nuclear deterrence is a risky business. The United States managed to avoid stumbling across the nuclear threshold with the Soviets, but there were close calls. There is every reason to want to avoid negotiating those shoals with North Korea.

As North Korea’s nuclear arsenal grows in credibility with each nuclear weapon and missile test, the available options for the United States don’t change much. Military options to take out North Korea’s arsenal are as bad now as they were before. There may be greater willingness to impose hard-hitting sanctions like cutting off oil, but the wide array of current sanctions is already not being faithfully implemented. North Korea’s nuclear trajectory has been frustrating and astounding exactly because the North seems impervious to the demands of the most powerful countries in the world.

A few months ago, Tillerson declared that the United States does not seek regime change or collapse, military operations in North Korea, or a hastened reunification of the two Koreas. Just how this fits in with the stated Trump policy of maximum pressure and engagement with the North Koreans remains to be seen. We know what maximum pressure would be. Now it’s time to see what engagement can do.

Sharon Squassoni is senior fellow and director of the Proliferation Prevention Program at the Center for Strategic & International Studies.