A U.S. aircraft carrier has sailed through the Strait of Hormuz into the Persian Gulf, a month after Iran warned the United States not to send carriers to that strategic waterway.

A spokeswoman for the U.S. Navy's 5th Fleet says the USS Abraham Lincoln entered the Gulf Sunday without incident for what she calls a regular and routine passage.

When the United States redeployed a carrier from the Gulf last month, Iran warned the Pentagon against sending another ship to the region. It did not specify what it would do, but Iranian officials backed down from their threat Saturday, calling the routine appearance of a U.S. carrier a normal event.

Tensions have grown between Iran and the United States in recent weeks. Washington is preparing new sanctions against Iran as evidence mounts that it may be trying to build nuclear weapons. The European Union also is planning an Iranian oil embargo.

Iran insists its nuclear program is entirely peaceful. It has threatened to respond to more sanctions by shutting down the Strait of Hormuz, a major oil shipping lane.

The United States has said it will not let that happen.