HOUSTON — President Trump’s decision to withdraw from the Iran nuclear deal has so far had no more than a muted effect on oil and gasoline prices. But that could easily change.

The full impact on global oil markets may not be seen for weeks or months. It will depend on how tightly the administration enforces new sanctions on Iran, and whether the entire deal collapses or can somehow be salvaged. That may well depend on the responses of a diverse cast of geopolitical actors from Moscow to Beijing to New Delhi since the United States imports no oil directly from Iran.

A cascade of unpredictable events may follow the administration’s action, one that could ultimately lead to compromise. If not, there could be even greater instability across the Middle East and possibly an oil-price spike.

The biggest wild card is how Iran will respond.

European leaders have urged Iran to continue to abide by the agreement to freeze its nuclear development, despite the American withdrawal. President Hassan Rouhani has said he wants to negotiate with the Europeans, Russia and China on terms for continuing the deal, but the country’s supreme leader, Ayatollah Ali Khamenei, has left the door open to resuming its nuclear program.