The Pentagon will deploy 1,500 troops to the Middle East, including missile defense and surveillance units, a senior official said Friday, in the Trump administration's latest step to address what it says are increased threats from Iran.

Acting Defense Secretary Patrick Shanahan said he had approved U.S. Central Command's request to deploy a Patriot missile battalion, intelligence and surveillance aircraft, a squadron of fighter planes and engineering capabilities to "improve our force protection and safeguard U.S. forces given the ongoing threat posed by Iranian forces ... and its proxies."

"The additional deployment to the U.S. Central Command area of responsibility is a prudent defensive measure and intended to reduce the possibility of future hostilities," he said in a statement.

The decision was made after a meeting late Thursday at the White House between President Donald Trump and top Pentagon leaders.

In recent days Shanahan has said that any new troop deployments would serve to ensure the protection of U.S. forces and avoid the risk of Iranian miscalculation that could lead to a broader conflict.

"Our job is deterrence. This is not about war," he said Thursday. "We have a mission there in the Middle East: Freedom of navigation, counterterrorism in Syria and Iraq, defeating al-Qaida in Yemen, and the security of Israel and Jordan."

Speaking outside the White House, Trump said that "a relatively small number of troops - mostly protective" were being sent to the region.

The type of forces the Pentagon is deploying does not indicate any impending ground offensive by the United States. Patriot missiles are designed to track and shoot down incoming missiles.

The decision comes as the Trump administration steps up pressure on Iran after pulling out of the 2015 nuclear accord negotiated by President Barack Obama. Since then, the Trump administration has increased sanctions, designated Iran's Islamic Revolutionary Guard Corps as a foreign terrorist organization and declined to renew waivers that allowed eight countries to buy Iranian oil.

In recent weeks, U.S. officials have cited new indications of possible Iranian attacks on American interests as a reason to send the USS Abraham Lincoln Carrier Strike Group, four B-52 bombers and Patriot missile defense batteries to the region. The State Department ordered the evacuation of all non-emergency personnel from Iraq, where Iranian proxy forces operate.

U.S. officials say they believe that Iran was behind sabotage attacks on four oil tankers off the coast of the United Arab Emirates this month. Iran has denied involvement in the incidents, which damaged the ships. Two of the ships were Saudi Arabian, one was from the U.A.E. and the fourth was Norwegian.

Rep. Mac Thornberry, R-Texas, the top Republican on the House Armed Services Committee, defended the increased military posture announced Friday, saying in a statement that it is "important that we make clear to Iran, in words and actions, that they cannot attack us with impunity."

But Democrats have expressed skepticism about the urgency of the threats and voiced concern that the White House under the leadership of national security adviser John Bolton, who has advocated for regime change in Iran, could rush into a conflict.

Rep. Adam Smith, D-Wash., the committee's chairman, called the new deployment "unsettling."

"Without a clearly articulated strategy, adding more personnel and mission systems seems unwise, and appears to be a blatant and heavy-handed move to further escalate tensions with Iran," he said in a statement.

The increased pressure prompted a backlash by Iran, which announced this week that it has quadrupled the pace at which it enriches low-grade uranium at one nuclear plant. It predicted that within weeks, it would exceed a stockpile cap set by the nuclear agreement.

A senior administration official on Friday accused Iran of using "nuclear blackmail" for threatening to stop meeting some of its commitments under the deal if the Europeans can't figure out a way to get around U.S. sanctions by early June.

"We are trying to work as closely as we can with our allies to get them to hold fast on these fairly negative attempts at nuclear extortion and not give in to Iran's demands," said the official, speaking on the condition of anonymity to a small group of reporters.

With Iran's accelerated pace of uranium enrichment and the looming deadline for the Europeans to throw it a lifeline, the official said the Europeans must choose "whether or not they will give in to this kind of extortion or stand firm and make clear to Iran that there is one viable path for them, and that is to come to the table with us."

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The Washington Post's Carol Morello and Anne Gearan contributed to this report.