The ultra-sensitive radar the U.S. uses to track ballistic missile targets was deployed off North Korea in September, according to local press reports.

Sea-Based X-Band Radar (SBX-1) an oil-derrick sized phased array radar was deployed off the Korean peninsula for about a month, according to a report in the South Korean newswire Yonhap.

“[SBX] was sent to an undisclosed location off the Korean Peninsula for a one-month deployment after departing Hawaii in late September,” a South Korean military official told the wire, reported Stars and Stripes.

“It sailed back to its home port in late October.”

The time off the peninsula would overlap with a recent string of North Korean intermediate range ballistic missile launches and would likely be recording key information from the launches.

The SBX-1 is a key component of the U.S. ballistic missile defense system and is sensitive enough to detect an object the size of a baseball at 2,500 miles, according to information from the Missile Defense Agency (MDA).

While U.S. officials did not confirm any details of the Yonhap report. The deployment of SBX-1 mirrors a 2013 deployment in which the radar was deployed off North Korea during a period of ballistic missile tests.

The news of the SBX-1 off of the peninsula comes as a Tuesday report from Fox News quoting U.S. officials that North Korea will conduct a launch of a Musudan intermediate-range ballistic missile within the next 24 to 72 hours.

“The pre-Election Day launch of the Musudan missile would be the ninth test launch this year, in addition to two nuclear tests by the communist nation in defiance of United Nations sanctions,” read the report.

Later this week, the U.S., the U.K. and South Korea will hold a trilateral air exercise centered on the Osan Air Base.

“The Invincible Shield drill is aimed at improving the allies’ capabilities of attacking North Korea’s major military and leadership facilities (if provoked) but also intercepting incoming fighters from the North,” a South Korean Air Force spokesman told Yonhap.

North Korea warned Britain to back out of the drills last month.

“This is a hostile act, openly joining the U.S. and South Korean forces in moves for a new war against us,” said North Korean Foreign Ministry official Pak Yun Sik, according to a report in The Associated Press.

“Britain claims that this military exercise is not targeting us, but the U.S. and South Korea openly say that these military exercises are aimed at launching a strike against our military facilities and our command structure.”