US President Donald Trump’s decision to order the assassination of Qassem Suleimani, Iran’s most powerful military commander, has raised the specter, albeit still distant, of all-out war between the United States and the Islamic Republic. There is only one winner in this situation: China.

The killing is a game-changer that will divert America’s attention from other priorities and force Trump to send more troops and weapons to the Middle East rather than withdrawing.

Protected by the vast Atlantic and Pacific oceans, the American homeland is a difficult target for direct retaliation. Iran and its proxies have easier marks around the world.

The Trump administration owes the world a clear explanation of how it justified an operation to kill Iranian Gen. Qassem Soleimani. So far, the strike seems legally dubious, if not flagrantly illegal.

Britain, France and Germany have shifted their position, but with the suggestion of permanent denuclearization in exchange for permanent removal of sanctions, Iranian Foreign Minister Javad Zarif may have kicked the ball back to the United States.

Saudi Arabia faces the prospect of becoming engulfed in in a war with Iran before it has fully extracted itself from the conflict in Yemen. Adjustments may follow, both diplomatic and domestic.

Strategically, politically and economically, Trump’s Iran policy is failing. Rather than force Iran into submission, Trump’s tactics have decreased Iran’s incentives to continue compliance with the nuclear deal. The era in which the United States could unilaterally push through its global agendas has come to an end.

President Trump must convince US allies of his positions toward Iran, or risk appearing as an erratic rogue actor while China and Iran seek to preserve a familiar status quo.

The recent US cyber-attack on Iran, in retaliation for the downing of its drone, raises new questions for the militarization of cyberspace: what are the norms governing cyber war? What are the implications for international cooperation on the global Internet? How can governments stop cyber-attacks from escalating in unpredictable ways? These matters greatly concern the US and China.