The U.S. Air Force has awarded Boeing Co. and Northrop Grumman Corp. separate contracts to continue work on the replacement of the aging Minuteman III intercontinental ballistic missile system, the Pentagon said on Friday.

Though the award for the new Ground-Based Strategic Deterrent (GBSD) comes amid rising tensions with North Korea, the Air Force had asked the defense industry last summer for proposals to replace the aging ICBM system and its nuclear cruise missiles as the military moved ahead with a costly modernization of its aging atomic weapons systems.

"The Minuteman III is 45 years old. It is time to upgrade," Air Force Chief of Staff General David Goldfein said in a statement on Monday.