We are growing more prosperous, and new technologies, medicines, and ideas are making our lives better. Still, the world remains dangerous. Here are five top threats to America in 2019.

1) A conflict with China over the South China Sea

Although President Trump and President Xi Jinping of China have a good personal relationship, tensions between our two nations are significant and growing. Aside from any economic developments, there is real potential for a military conflict between the U.S. and China in 2019. If conflict breaks out, it will almost certainly focus on the South China Sea. Determined to construct an imperial empire based on control of sea lanes and to attain a veto over the political choices of his neighbors, Xi is exerting an aggressive military posture. While the U.S. is challenging these efforts with increasing naval and air patrols through the contested areas, a miscalculation or Chinese escalation could lead to a broader conflict. It is crucial to note here that Xi is determined to see China lead a new post-American international order. He will not back down easily, nor shy from risks.

2) North Korea brinkmanship

I believe that U.S.-North Korea tensions will escalate this year. While Trump and North Korean leader Kim Jong Un are likely to hold another summit, the North Korean leadership is indicating that it is unlikely to offer meaningful concessions. The absence of those concessions will mean that the U.S. can offer no sanctions relief to Pyongyang. The North Koreans need that relief. What will North Korea do then? I suspect Kim will conduct another missile test. That test will be designed to win U.S. appeasement of Pyongyang, but also to advance North Korea's intercontinental ballistic missile program. But if a new test does occur, the U.S. will have to impose new sanctions. A U.S. military strike on North Korea's nuclear and ballistic missile infrastructure will also become more likely. That risks a new Korean war.

3) Russian attacks on U.S. interests

Russia continues to develop its ability to contest NATO in war. While Defense Secretary Jim Mattis (Monday is his last day in office) helped to fill in the alliance's weaknesses, Vladimir Putin's threat will remain very real this year. The Russian leader is determined to rebuild a Soviet-style architecture of deference to Moscow among Russia's neighbor states. But as those states grow closer to the west, Putin will have to choose between tolerating that movement or confronting it more directly. All signs suggest he will choose some kind of confrontation. U.S. allies must do more to help deter and defeat this threat.

4) Major terrorist attacks

The Islamic State may have lost much of its territory, but experienced fighters and commanders remain operational and determined to continue their war. The threat of a major attack on U.S. or allied interests remains significant. Other groups such as al Qaeda also prioritize attacking the West. In addition, Iranian terrorist operatives-proxies remain active in Europe and around the world. In the worst-case scenario, it remains possible, albeit unlikely, that terrorists would access and use a weapon of mass destruction.

5) An enveloping conflict in the Middle East

As Iran grows in power and ambition in Syria, hardliner elements in Tehran will likely escalate their campaigns against the Sunni-Arab monarchies and Israel. Those nations are likely to reciprocate the aggression in kind. If, for example, an Iran-proxy missile attack causes casualties in northern Israel or Riyadh, major retaliation might follow. That risks a broader war which reverberates through Lebanon, Iraq, and against direct U.S. interests. Escalated U.S. balance of power efforts are critical.

None of the above may come to pass. But these threats indicate why the U.S. requires a powerful military and military leaders who mitigate evolving U.S. vulnerabilities.