WASHINGTON — The vice chairman of the U.S. Joint Chiefs of Staff expressed confidence about an upcoming intercept test of the troubled U.S. national missile shield, but acknowledged that the pressure to have a success is higher than usual.

“I’m not going to sit here and predict it will be a 100 percent chance that it will be a success, but I think we’ve dramatically raised the odds it will succeed next month,” Navy Adm. James “Sandy” Winnefeld said May 28.

The test — known as FTG-06b — will help determine whether the Pentagon is ready to buy 14 more Ground-based Midcourse Defense (GMD) interceptors for installation at Fort Greely, Alaska. The planned purchase is a key part of the Obama administration’s plan to bolster the nation’s defenses against an attack from North Korea, a country that Winnefeld described as the United States’ No. 1 missile defense priority.

“I personally don’t think it’s going to fail,” Winnefeld said at a missile defense conference hosted by the Atlantic Council here. Nonetheless, if the test were to fail, he said, “I don’t think it would be a shot to the head. … We’re still committed to this program.”

The GMD has failed in three straight intercepts dating back to 2010. At least two of those failures have been attributed to issues with a critical piece of hardware known as the Exoatmospheric Kill Vehicle, or EKV, which is designed to separate from the GMD booster rocket in space and home in on the target missile, destroying it by direct impact. These factors have led to additional scrutiny to the program, a fact Winnefeld acknowledged in answering questions from the audience.

The EKV is manufactured by Raytheon Missile Systems of Tucson, Arizona. Boeing Defense, Space & Security of St. Louis is overall prime contractor on the GMD.

“We are very focused on the success of that test,” Roger Krone, president of Boeing Network and Space Systems, said in a meeting with reporters May 13.

All told, the GMD system has recorded eight intercepts in 16 attempts since 1999.

Winnefeld said his confidence in the upcoming test stems in part from a January 2013 nonintercept test at Vandenberg Air Force Base, California, that he characterized as “an amazing success.” During that test, the interceptor performed “a variety of pre-planned maneuvers to collect performance data in space,” the Defense Department said in a press release at the time.

But Winnefeld also acknowledged what many critics have long been saying about the EKV and other missile defense programs: that the hardware was rushed through design and into production.

“It’s amazing we did as well as we did,” he said.

The House version of the 2015 national defense authorization bill, which passed in May, includes language that would prohibit the U.S. Missile Defense Agency from buying any more of the current EKVs pending successful completion of this summer’s planned intercept.

Either way, the agency intends to move forward with development of a new EKV. The Pentagon’s 2015 budget request includes nearly $100 million to redesign the kill vehicle that tops the GMD interceptors.

“It’s time for us to look at new technologies,” Winnefeld said.

Throughout his speech, Winnefeld also repeatedly sought to dispel any notion that the U.S. European Phased Adaptive Approach missile defense plan, which currently relies on ship-based Standard Missile 3 interceptors that starting in 2015 would be installed on land in Romania, is aimed at Russia’s strategic deterrent force.

Winnefeld said Russia’s strategic missile fleet is too big and too sophisticated to be hindered by U.S. interceptors in Romania, or even by more capable variants slated for installation in Poland starting in 2018.

Mike Gruss covers military space issues, including the U.S. Air Force and Missile Defense Agency, for SpaceNews. He is a graduate of Miami University in Oxford, Ohio.