Amid heightened tensions over North Korea, the Liberal Democratic Party has stepped up calls to boost Japan’s missile defense in what some experts see as a move to gauge reaction from the public and regional powers, including the United States, about the potential adoption of strike capability.

Despite an agreement between U.S. President Donald Trump and Chinese leader Xi Jinping during a two-day meeting in Florida through Friday to step up coordination on reining in North Korea, uncertainty persists that Pyongyang may push ahead with a sixth nuclear test and keep test-launching ballistic missiles in an effort to improve its nuclear and missile programs.

The LDP has proposed introducing the advanced U.S. missile defense system known as the Terminal High Altitude Area Defense (THAAD) and other state-of-the-art military assets, as well as acquiring the ability to strike an enemy base, such as with cruise missiles.

LDP lawmakers versed in security affairs say they were highly alarmed by the simultaneous firing March 6 by North Korea of four ballistic missiles — three of which landed inside Japan’s exclusive economic zone in the Sea of Japan — and Pyongyang’s announcement that the action was a drill simulating a strike on U.S. military bases in Japan.

“North Korea’s provocative acts have reached a level which our country can never overlook,” the LDP Research Commission on Security said in a proposal submitted March 30 to Prime Minister Shinzo Abe.

China immediately criticized the proposal, apparently concerned about a Japanese military buildup and the possibility that such measures could also be used against Beijing.

“China is opposed to any country’s act of using the (North Korean) missile issue as an excuse to compromise other countries’ security and regional stability,” Ministry of National Defense spokesman Wu Qian said at a press briefing March 30.

While U.S. officials and experts will likely back the LDP’s call on Abe to “immediately consider” introducing THAAD, Aegis Ashore ( a land-based variant of the Aegis ballistic missile defense system) and other systems, they appear to be divided over the party’s proposal that the government “immediately consider” acquiring strike capability.

“The U.S. welcomes and wants Japan to have the ability to defend itself and to be able to contribute more to regional attempts to counter the missile threat posed by North Korea,” said Brad Glosserman, executive director of the Pacific Forum Center for Strategic and International Studies, a Hawaii-based think tank.

“But the THAAD and strike options are very different. One is purely defensive and the other is offensive defense,” Glosserman said.

Strike options “increase the chances of escalation in a crisis and the U.S. is not the one with its finger on the button, meaning we (the U.S.) have less control over the situation,” he said.

Adm. Scott Swift, commander of the U.S. Pacific Fleet, said he would not be surprised to see discussions on strike capability progressing in Japan, given the rising threat posed by North Korea’s missile and nuclear weapons development, including another ballistic missile launch last Wednesday.

If Japan decides to possess such capability, it would not be difficult for the U.S. to make adjustments because of the extremely close ties between the Self-Defense Forces and the U.S. military, Swift said in a group interview Thursday in Tokyo.

The LDP proposal said the envisioned strike capability aims to “further enhance deterrence and response capabilities of the Japan-U.S. alliance” against the North Korean threat.

Itsunori Onodera, a key member of the commission, also said the proposal does not call for a first-strike capability, but rather the ability to strike back in the defense of Japan.

“It naturally falls within the scope of self-defense to neutralize the opponent as a way to prevent it from launching a second attack,” Onodera told reporters in Tokyo, stressing that such a measure would not violate the war-renouncing Constitution.

Glosserman, however, argued that if it were merely a retaliatory capability, “there is an implicit message that Japan does not trust the U.S. to act on its behalf. That is worrisome.”

Upon receiving the proposal March 30, Abe did not comment directly, only saying he “takes the new level of threat (posed by North Korea) seriously” and that he “would like to coordinate with the party going forward.”

“This kind of discussion is not random,” Glosserman said, noting that Onodera, who previously served as a defense minister under Abe, and other like-minded lawmakers would not present such a proposal without the prior consent of the prime minister.

One wildcard will be how the Japanese public perceives the proposed strike capability.

Abe, an advocate of Japan playing a larger security role, deeply divided the public in 2015 when he pushed controversial legislation into law that enables the SDF to help defend the U.S. and other friendly nations under attack.