WASHINGTON (AP) ― Amid concerns about its development and testing of nuclear weapons, North Korea may be lulling the world into largely accepting its advances in missile technology, the admiral in charge of American forces in Asia and the Pacific said Tuesday.

Adm. Samuel Locklear told a Pentagon news conference that he is concerned by North Korea’s frequent testing of ballistic missiles. Locklear heads U.S. Pacific Command, and his responsibilities include military relations with longtime U.S. ally South Korea.

North Korea often test-fires missiles, artillery and rockets, but the number of weapons tests it has conducted this year is much higher than previous years.

“Every time they do something that the international community has told them not to do, particularly as it relates to missile technology or nuclear technology, you have to assume that it’s a step forward in technology,” Locklear said. “Otherwise, they probably wouldn’t be doing it.”

Locklear said he worries that “you become somewhat numb” to reports of another North Korean missile test, adding, “you start to say, well, it’s not such a big deal.”

In the latest signs of international concern, a U.N. Security Council committee on Monday imposed sanctions on a North Korean shipping company that operates a ship seized last year by Panama for carrying undeclared military equipment from Cuba.

The North Korean company is suspected of helping arrange the shipment of arms in violation of a U.N. arms embargo imposed against Pyongyang in response to North Korea’s nuclear and missile programs.

Locklear said this and other recent developments highlight the importance of partnering with other countries to counter illicit North Korean weapons activities.

The admiral referred to a counterproliferation exercise, dubbed Fortune Guard 2014, that is scheduled to take place from Aug. 4-7 in and around Hawaii. Portions of the exercise will be at sea, including a role-playing event involving service members boarding a vessel as an interdiction rehearsal.

It is the first such exercise hosted by the U.S. in the Pacific. The U.S. has invited 35 nations to participate, including China, and 18 countries have agreed. Confirmed participants include Australia, Japan, South Korea, Cambodia, Malaysia, Vietnam, Canada, India, Indonesia and Thailand.

Exercises of this type are aimed at deterring or stopping the spread of a variety of weapons and weapon technologies in the Pacific, but the biggest concern is nuclear weapons and one of the most targeted violators is North Korea.

U.S. officials say efforts to secretly move weapons of mass destruction have become more sophisticated, with the weapons often being broken into pieces in order to better camouflage their delivery.

A senior defense official said the weapons parts are more frequently being moved by commercial air and ground transport rather than by ship, which had been the most prevalent method in the past. And weapons proliferators are often using multiple pathways and transit routes to evade detection.

The official spoke on condition of anonymity in order to discuss intelligence-related details about U.S. efforts to counter the spread of illicit weapons.