North Korea fired a ballistic missile on Sunday, amid discussions of a pre-emptive strike on it in the US.

Analysts say it launched an intermediate-range missile instead of an intercontinental ballistic missile, apparently heeding US warnings against ICBM development.

By firing a missile Sunday, North Korea seems to have abandoned its wait-and-see attitude toward the Donald Trump administration. It has shown its will to go its own way, no matter what happens.

North Korea should know the US has turned tough on its nuclear and missile development under Trump.

US Sen. Bob Corker, chairman of the Senate Committee of Foreign Relations said Washington should think “outside the box” regarding its strategy toward Pyongyang, and that one example is to be prepared to pre-emptively strike against a North Korean ICBM.

US Secretary of State Rex Tillerson said he would keep all options on the table, including the threat of military force.

According to some experts here, the US government appears to have the will and ability to pre-emptively stop North Korea from developing nukes and ICBMs. Washington considered striking a small nuclear reactor at Yongbyon in 1994 to prevent North Korea from recovering raw material to make nuclear bombs.

For now, a pre-emptive strike appears unlikely because of the possibility of counterattacks and war. But if North Korea crosses a red line, the US may take action to protect its people. However, such an extreme step must never be taken without South Korea’s knowledge.

North Korea’s nuclear and missile program is directly related to the survival of South Korea. An acute division in public opinion is risky to national security. All presidential hopefuls condemned the Sunday’s missile launch. Regarding national security, they should make bipartisan efforts.

To thaw frozen relations between South and North Koreas is important, but in a situation where North Korea continues missile provocations, an election pledge to revive inter-Korean projects that can flow money into the Pyongyang regime is risky. Such projects also will violate the international sanctions upon the despotic state.

North Korea is expected to keep trying to upgrade its missile technology. South Korea should build up its missile interception capability, accordingly. It needs to proceed with the deployment of a US missile defense system as planned, while maintaining an unwavering alliance with the US.

North Korea’s missile launch is a flagrant breach of a related UN Security Council resolution.

Despite sanctions, Pyongyang has conducted nuclear and missile tests. Thae Yong-ho, a former North Korean diplomat who defected to South Korea, said that Kim plans to develop nuclear weapons at all costs by the end of 2017.

The effectiveness of sanctions needs to be raised enough to pressure Kim to give up his nuke and missile plan. To do so, China’s cooperation is essential. China has joined UN sanctions on North Korea, but has always been negative about penalizing its ally, saying the livelihoods of North Korean residents should be considered.

But Sunday’s missile launch may have embarrassed China. China had denied Trump’s claim that Beijing isn’t doing enough to rein in North Korea. It also had cautioned Trump not to escalate the already tense situation on the Korean Peninsula.

The point is whether Beijing will take a tough, persistent line against Pyongyang.

China reportedly arrested many officials of a Chinese company last September for their illegal trade with North Korea despite a UN resolution. But most are said to have been released later. Trade between the two countries has not noticeably been reduced.

The security environment of the Korean Peninsula is different from the past. North Korea is stepping closer to the completion of its nuclear and missile program. The US is considering taking military action if North Korea crosses the Rubicon.

At present one of the best ways to deter North Korean nukes and missiles is putting it in a straitjacket of sanctions.

Sanctions will be effective when they are watertight.