President Trump says the U.S. Navy should fire on Iranian boats if they continue to harass U.S. warships in the Gulf, a move that raises the prospect of open hostilities between the two rivals.

The president's Wednesday morning tweet came shortly after Iran announced it had successfully launched a military satellite into orbit for the first time.

With the U.S. and Iran both battling to control a coronavirus outbreak at home, the ongoing friction between the two countries had receded from the headlines.

But Wednesday's developments point to an escalation of tensions that have been building in recent days.

Last week, U.S. military ships were in the northern Persian Gulf for exercises. The U.S. warships were in international waters, though relatively close to Iran.

Iran sent small boats, known as "fast boats," toward the American warships, with one coming as close as 10 yards, according to the Navy, which released a video. The Pentagon accused Iran of sending 11 fast boats to make "dangerous and harassing approaches" to six American warships.

These kinds of standoffs in the Gulf have been taking place for many years. The U.S. and Iran usually observe unwritten rules and the confrontations rarely escalate into actual hostilities, with occasional exceptions.

However, Trump's instruction for the Navy to shoot Iranian boats raises the ante.

Air Force Gen. John Hyten, the vice chairman of the Joint Chiefs of Staff, spoke to reporters at the Pentagon shortly after Trump tweeted. Hyten said he "liked that the president warned an adversary."

"If we see a hostile act, if we see hostile intent, we have the right to respond up to and including lethal force, and if it happens in the Gulf, if it happens in any way, we will respond with overwhelming lethal force if necessary to defend ourselves," Hyten added.

Rob Malley, head of the International Crisis Group, criticized the president's move.

"The administration's Iran strategy is premised on the notion that Tehran will give in under military threats and economic siege," Malley said. "That premise seems to have it precisely upside down. Doubling down on the same failing tools isn't going to yield a different outcome. It's time for a course correction before the two sides fall into a military confrontation both claim not to want."

In a separate development also likely to heighten tensions, Iran's Revolutionary Guard Corps said it had launched a military satellite into orbit for the first time. This raised the possibility that Iran could use the technology to develop intercontinental ballistic missiles.

"Today, the world's powerful armies do not have a comprehensive defense plan without being in space, and achieving this superior technology that takes us into space and expands the realm of our abilities is a strategic achievement," Gen. Hossein Salami, the leader of the Revolutionary Guard, was quoted as saying by The Associated Press.

Trump has pursued a policy of "maximum pressure" against Iran, which has included the U.S.'s unilateral withdrawal in 2018 from an international nuclear deal with Iran.

Iran has subsequently abandoned the limitations of the treaty and has pushed to expand its capabilities in areas outside the treaty, including satellite launches. Iran experienced several failed launches in recent months.

U.S.-Iran tensions ratcheted up near the end of last year. In January, the U.S. carried out an airstrike that killed Iran's most prominent military official, Qassim Soleimani. Iran responded with missile strikes on military bases in Iraq that were hosting U.S. forces.

The two countries pulled back from that confrontation, but the latest developments point to the possibility of a new round of tensions.

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