May 4 (UPI) -- U.S. Navy and Air Force spy planes flew near North Korea several times in recent days, as Pyongyang condemned Washington's North Korea policy and the latest satellite imagery showed activity at Nampo shipyard.
Aircraft tracker RadarBox disclosed data of movements of the U.S. Air Force's Joint STARS E-8C aircraft and the U.S. Navy's EP-3E Aries. Both aircraft were deployed at the end of April, South Korean news service News 1 reported Tuesday.
The E-8C flew over the West Sea or Yellow Sea, between China and the Korean Peninsula on April 25, Wednesday and Thursday. The EP-3E flew over the Korean Peninsula on April 27. The timing of the flights coincided with last week's North Korea's Kimilsungist-Kimjongilist Youth League.
The tracker also showed both spy planes were deployed Sunday, when Pyongyang issued three separate statements critical of the United States and South Korea.
The E-8C is capable of detecting targets at more than 155 miles. The EP-3E can intercept signals and usually carries a crew of linguists, cryptographers and technicians.
The E-8C has been regularly deployed in the peninsula in recent months.
In January, ahead of the opening of North Korea's Eighth Party Congress, online tracker NoCallSign reported movements of the E-8C. The plane flew over the Seoul Metropolitan area at the time, according to South Korean newspaper Chosun Ilbo. On Jan. 9, a day after the opening of North Korea's Eighth Party Congress, the U.S. spy plane flew over the Seoul metropolitan area, according to News 1.
South Korea's joint chiefs of staff said Monday that there has been no unusual activity this week.
Last week South Korea's Joint Chiefs of Staff public affairs chief Kim Joon-rak said North Korea appeared to be upgrading submarines.
On Sunday, North Korea warned the United States against adhering to a "hostile policy."