The Trump administration is hitting Iran with new sanctions that target its largest petrochemical company for providing support to the Revolutionary Guard Corps.

The Treasury Department says the sanctions will apply to the Persian Gulf Petrochemical Industries Company and 39 of its subsidiaries and foreign sales agents. It says the company holds 40% of Iran's petrochemical production capacity and is responsible for 50% of the country's petrochemical exports. Treasury says the companies have done billions of dollars of business with the Guard Corps, which the administration designated a "foreign terrorist organization" last month.

"By targeting this network we intend to deny funding to key elements of Iran's petrochemical sector that provide support to the IRGC," said Treasury Secretary Steve Mnuchin.

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The sanctions are part of the administration's "maximum pressure" campaign against Iran and freeze any assets the targeted firms may have in U.S. jurisdictions and bar Americans from doing business with them.

The sanctions come amid escalating tensions with Iran. President Trump warned Iran in a tweet in May not to threaten the United States again or it would face its "official end," shortly after a rocket landed near the U.S. Embassy in Baghdad overnight.

The U.S.S. Abraham Lincoln is conducting regular training exercises in the Arabian Sea. The carrier was specifically sent there as a deterrent in response to what the Trump administration believes are threats from Iran. But it has yet to go through the Strait of Hormuz, a crucial channel for the world's oil trade and a potential flashpoint with Iran.

U.S. military officials and the White House have definitively laid blame for an attack on three oil tankers last month on Iran, as has close U.S. ally and Iranian arch-rival Saudi Arabia.

Meanwhile, the chief of U.S. Central Command, Gen. Frank McKenzie, told reporters Friday that he remains concerned about the threat from Iran and that he would not rule out requesting additional U.S. forces to the Middle East.

"I don't actually believe the threat has diminished," McKenzie said Thursday. "I believe the threat is very real."