The United States requires a system to protect its satellites and space assets from enemy attack, a key senator said.

Sen. James M. Inhofe (R-Okla.) voiced concerns during a Senate Armed Services Committee strategic forces subcommittee hearing, after China in January used a ground-based missile to destroy one of its aging weather satellites in orbit.

Many military analysts say this shows that China has the ability to destroy U.S. military satellites, possibly blinding American armed forces just as China would launch a long-threatened invasion of Taiwan.

Lt. Gen. Henry “Trey” Obering III, the Missile Defense Agency (MDA) director, noted that MDA has “not been assigned to do” an anti-satellite mission.

Inhofe replied that the primary concern isn’t which agency would provide the protection, but rather that some agency should erect such a shield.

“This is something that really concerns me,” he said. He wants protection from such anti-satellite attacks, “whether it’s you [MDA] or someone else” providing the defense.

What MDA is charged with is providing a multi-layered, multi-program shield against incoming enemy ballistic missiles. Threats include North Korea, which is developing both nuclear weapons and long-range missiles, and Iran, which is producing nuclear materials and last year fired a missile from a submerged submarine.

On the overall mission, MDA drew high marks from the leading Pentagon testing chief.

The MDA has a “robust” program to develop anti-missile systems, and they are “maturing in a satisfactory way,” Charles E. McQueary, director of operational test and evaluation, said. The MDA “has had a good year” in tests, he said.

Further, MDA “has been very responsive” to input from the testing and evaluation office, MdQueary said. Overall, the multiple ballistic missile shield already is demonstrating “a limited capability” against certain types of threats, he told the senators.

Senators also asked about MDA plans to create a small ballistic missile defense center in Europe to guard Europe, U.S. troops and others in the region from attack by missiles launched from the Middle East, with worries centered on Iran.

The United States faces “increasing Middle Eastern missile threats,” Brian R. Green, deputy assistant secretary of defense for strategic capabilities, told senators.

To counter those threats, the United States has proposed installing a ground-based ballistic missile defense system with 10 interceptors in Europe.

Some senators asked pointed questions, such as whether the Czech Republic has agreed to installation of a radar, whether Poland has agreed to installation of ground silos for interceptor missiles, and whether NATO has approved installation of the overall European ballistic missile defense (BMD) system.

Later, the Missile Defense Advocacy Alliance said any lawmaker who might oppose such a system should first answer two questions: with Iran likely to have longer-range missiles by 2015 at the latest, if the European BMD system isn’t built and stood up, then what will protect Europe and U.S. forces there? And since when has the United States permitted NATO to exercise veto power over U.S. military advancements?

“Missile defense continues to be one of the administration’s highest priorities,” Green said, citing the belligerence of Iran and North Korea.

The United States no longer can depend solely on its massive nuclear offensive capabilities to dissuade some potential enemies from firing missiles, and American forces therefore require missile defense, Green said.

The Government Accountability Office (GAO) objected that MDA has budgetary flexibility atypical of a defense agency, which makes it difficult to hold MDA accountable for costs and program outcomes.

But Paul Francis, GAO director of acquisition and sourcing management, said that while MDA “continues to identify quality assurance weaknesses … the agency’s corrective measures are beginning to produce results. Quality deficiencies are declining as MDA implements corrective actions, such as a teaming approach designed to restore the reliability of key suppliers.”

Aside from quality, quantity concerns are being addressed. “With the possible exception of” ground-based missile defense “interceptors, MDA is generally on track to meet its revised quantity goals,” Francis told senators.