Washington (CNN) -- Due to security concerns in Jordan, which borders the Syrian civil war, a combat-equipped detachment of about 700 U.S. troops will remain in the country following training exercises that ended this week, President Barack Obama told Congress on Friday.
In a letter to comply with the War Powers Act, Obama notified Congress that the detachment staying behind at the request of the Jordanian government included "Patriot missile systems, fighter aircraft, and related support, command, control and communications personnel and systems."
"The detachment will remain in Jordan, in full coordination with the government of Jordan, until the security situation becomes such that it is no longer needed," Obama's letter said.
A flood of refugees from the Syrian conflict is considered potentially destabilizing for Jordan, a key U.S. ally in the region. In addition, the possibility of cross-border missile fire or other attack raises concerns of an unwanted escalation in the volatile Middle East.
"The deployment of this detachment has been directed in furtherance of U.S. national security and foreign policy interests, including the important national interests in supporting the security of Jordan and promoting regional stability, pursuant to my constitutional authority to conduct U.S. foreign relations," Obama's letter said.
CNN Pentagon Correspondent Barbara Starr previously reported that U.S. troops would remain in Jordan beyond the training exercises that concluded Thursday. Obama's letter Friday put the figure at around 700.
The Patriot missiles would be used to defend Jordan against any missiles launched from Syria, according to Starr's report. A senior U.S. military official told Starr that F-16 fighter jets "send a message" to Syria that the United States will defend Jordan if necessary.
In addition, another 200 or so troops specializing in military planning from the 1st Armored Division's headquarters were scheduled to arrive later this summer in Jordan, Starr previously reported.
The planning troops were to replace existing planners with a more focused ability to help Jordan's commanders prepare for any number of Syrian contingencies, including a chemical weapons crisis or a worsening refugee situation, according to Starr's report.
At the same time, U.S. Marines were continuing a longstanding presence in Jordan of about 130 personnel to train Jordanian units slated to go to Afghanistan. Officials acknowledged to Starr that the counter-terrorism training could be used in any crisis.
Meanwhile, the U.S. Navy also was continuing its longstanding deployment of three anti-ballistic missile ships is the eastern Mediterranean. The ships, with a total crew of about 1,000, carry Tomahawk cruise missiles to defend Israel from any attack by Iran.
Several Navy officials said the U.S. ships also could defend Jordan or Israel against any Scud missile launch from Syria.
Last week, the Obama administration announced it was increasing aid to Syrian rebels, including military assistance, after determining government forces had used chemical weapons. The administration has yet to provide details of the military assistance it would provide, but sources indicated it would be light arms and ammunition, and perhaps anti-tank weapons.
Senior U.S. officials have said there was continuing concern that eventually some type of military units will be needed to go into Syria to take control of chemical weapons stockpiles. For more than a year, the United States has quietly trained Jordanian forces for that mission, Starr previously reported.
CNN's Jim Acosta contributed to this report.