(CNN) - President Donald Trump will visit the Pentagon on Thursday to unveil his administration's long-awaited missile defense review, multiple officials tell CNN.
Officials said the review is expected to embrace putting advanced sensors in space in a bid to better detect enemy missiles, allowing the US military to intercept them even earlier.
A senior administration official speaking to reporters on the condition of anonymity that while that a space-based layer of satellite sensors "is something we're looking at to help give early warning tracking," the review stopped short of calling for the deployment of interceptors in space.
The official said the review calls for "further studies" of space-based counter-missile technology like interceptors or lasers and does not "direct the fielding of anything or the development of anything specific."
Trump will be accompanied by Vice President Mike Pence, national security adviser John Bolton, and senior military and defense officials.
Trump initially ordered that the review be carried out in January 2017, his first month in office, but it has been long delayed. it was originally scheduled to be released in late 2017, and in February 2018.
This is the first missile defense review since the Obama administration carried one out in 2010.
The official said the new review was conducted because "we've seen a pretty significant change to the threat environment" since 2010.
The official said the administration was "expanding the scope of what we're postured to defend against with this new review," saying it focused on hypersonic and cruise missiles as well as ballistic missiles, something the previous review did not do.
Pentagon officials have long warned about advancements in hypersonic and cruise missiles being made by Russia and China and, late last month, Russian President Vladimir Putin unveiled a hypersonic missile he claimed was "invulnerable" to US defenses.
The Russian "Avangard" is said to have an intercontinental range and the ability to fly as fast as Mach 20, more than 15,000 mph.
China is also seeking the technology, with the US Defense Intelligence Agency publishing a report Tuesday saying China's military "is developing a range of technologies to counter US and other countries' ballistic missile defense systems," including maneuverable re-entry vehicles, decoys and hypersonic glide vehicles.
When asked about relations with Russia and China -- and whether an expansion in defensive capabilities would potentially signal an offensive move -- the official noted the "good relations" between Trump and Russian and Chinese leaders, while praising the transparency of the US's missile defense posture.
"With respect to relations with Russia and China, the President ... relies on having good relations with the leaders of both of those countries," the senior administration official said during the call with reporters Wednesday. "Our defense capabilities are purely defensive. The United States has been very transparent throughout the development of its missile defense capabilities about what they are posturing to defend against."
With regard to the missile threats from Russia and China, the report is expected to say that the US will rely on deterrence, by having the military be able to conduct a retaliatory strike that would discourage Moscow or Beijing from attacking.
The official added that the missile defense capabilities "are primarily postured to stay ahead of rogue state threats," pointing to Iran as an example.
"So you know, the forces, for example, that we have positioned in Europe are there to deal with extra-regional threats like those that come from Iran," the official said.
As part of this "comprehensive look" at US missile defense capabilities, the senior administration official said the review "discusses the possibility of a third interceptor site in the continental United States, for example."
Currently the US military's Ground-Based Interceptors are emplaced at Fort Greely, Alaska, and Vandenberg Air Force Base, California.
The interceptor missiles are able to intercept an enemy missile in midflight. A total of 44 interceptors are in place, according to the Missile Defense Agency.
When pressed to elaborate on the possibility of a third interceptor site, the official stressed that no decision had been made yet.
"That's something we have been considering. We've done an environmental impact study on three potential sites. So we're ready to move forward if it's determined that that's something that would really enhance our posture with respect to Iran. But no decision has been made about a third interceptor site yet," the official said.
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