SEOUL — (CNN) North Korea fired a projectile into the Sea of Japan, also known as the East Sea, on Wednesday morning, US and South Korean officials said.

The United States believes the projectile was likely a ballistic missile, according to a US official. It is one of several the country has test-fired in recent months.

The test elicited a terse response from the US State Department, unlike the standard diplomatic condemnations that usually follow Pyongyang’s missile tests.

“North Korea launched yet another intermediate range ballistic missile. The United States has spoken enough about North Korea. We have no further comment,” US Secretary of State Rex Tillerson said in the statement.

South Korea’s Unification Ministry spokesman, Lee Duk-Haeng, said the launch was a “threat against peace and stability.”

Japanese Prime Minister Shinzo Abe also condemned the launch and said the country’s National Security Council would meet on the issue.

North Korea’s missile test comes just a day before Chinese President Xi Jinping visits US President Donald Trump for a summit in Florida, and as the US, Japan and South Korea wrap up a round of trilateral naval military drills off the Korean Peninsula.

The United States has been pushing China to put pressure on North Korea to stop its nuclear program and missile testing, but Trump said on Sunday the United States would be prepared to act alone to stop North Korea.

A senior White House official on Tuesday said: “The clock has now run out, and all options are on the table,” pointing to the failure of successive administrations’ efforts to negotiate an end to the country’s nuclear program.

In his first five years as North Korean leader, Kim Jong Un has overseen more than double the number of missile tests than his father did during his 17-year rule, according to the Center for Strategic and International Studies.

The primary concern surrounding North Korea’s weapons program is that Pyongyang could eventually equip long-range missiles with a nuclear warhead.

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North Korea has conducted five nuclear tests — including two last year — but experts said the country still hasn’t developed nuclear warheads that can be mounted onto missiles.

“Before the end of President Trump’s current term, the North Koreans will probably be able to reach Seattle with an indigenously produced nuclear weapon aboard an indigenously produced intercontinental ballistic missile,” Michael Hayden, who served as the director of the CIA between 2006 to 2009, said Tuesday while speaking at Johns Hopkins University.

Hayden went on to call North Korea the intelligence community’s toughest target on the planet.

Sinpo shipyard

Both US and South Korean officials said the projectile was a KN-15 medium-range ballistic missile. It was launched Wednesday at 6:42 a.m. Seoul time from a site in the vicinity of Sinpo, South Hamgyong province, a South Korean Defense Ministry official said.

It flew a distance of around 60 kilometers (37 miles) and flew as high as 189 kilometers (117 miles), South Korean officials said. Cmdr. Dave Benham, spokesman for US Pacific Command, said it was tracked for nine minutes and did not pose a danger to North America.

Those details raised questions with some experts — if the tracking time and distance are accurate, North Korea would have fired “the world’s slowest missile,” according to Melissa Hanham of the East Asia Nonproliferation Program.

“This test compared to the last one (in February) did not go as far or as high,” she said. “They may have been trying to test one stage.”

The North Koreans use Sinpo shipyard for their submarine activity, and US satellites have observed increased activity there in recent days, another US official said.

Solid fuel missile

The KN-15, which the North Koreans call the Pukguksong-2, is a medium-range ballistic missile and a land variant of the KN-11, a submarine-launched ballistic missile. US officials said the latest missile launch used a solid-fueled rocket from a mobile launcher.

The mobile launcher is concerning because it’s harder to detect and preemptively strike, according to Carl Schuster, a professor at Hawaii Pacific University and former director of operations at the US Pacific Command’s Joint Intelligence Center.

“It can roll out of a tunnel and launch on short notice,” Schuster told CNN.

Solid fuel-powered missiles are easier to move and launch than their liquid fuel counterparts. That makes them difficult for those monitoring North Korea’s military movements to spot, as there are fewer indicators, such as movement of trucks, for South Korean or US satellites and other surveillance to pick up on.

North Korea’s liquid fuel-powered ballistic missiles up until now required a garrison, fuel storage tanks and support vehicles to launch, which can be identified with imagery, experts say.

Solid fuel is like an explosive jelly, less corrosive than liquid fuel, and it can be more easily stored in the rocket’s fuel tank than the liquid alternative, which requires specially lined tanks.

“If this is the KN-15, North Korea is refining their solid fuel capabilities,” says David Schmerler, a research associate at the James Martin Center for Nonproliferation Studies. “It should be concerning everyone because it will be improving the chance to use their offensive capabilities better.”

And with an uptick in tests, North Korea may have significantly advanced its missile technology and increased the size of its arsenal, Schuster said.

Or Pyongyang could be bluffing.

“It very well may be a bluff that is intended to convince us that a unilateral preemptive strike is impractical, unrealistic and unwise,” Schuster said.

The-CNN-Wire ™ & © 2017 Cable News Network, Inc., a Time Warner Company. All rights reserved. (PHOTO: North Korea state media via CNN)