By Mike Stone

(Reuters) – U.S. military leaders told a congressional committee on Wednesday that their ability to prepare to counter adversaries such as Russia and China will be impaired if Congress does not provide certainty about their budgets.

U.S. Army Chief of Staff General Mark Milley showed his frustration following years of uncertainty by telling the House Armed Services Committee he would consider it “professional malpractice” if Congress fails to pass a budget.

Milley was among the four heads of the U.S. military services testifying to the committee on the potential impact of a continuing resolution, a stopgap funding measure Congress could extend if it does not pass the 2017 budget by the end of April.

Current Defense Department funding is set to expire on April 28. If a budget bill is approved, it would allow the military its traditional authority to start new programs and distribute money with relative autonomy.

President Donald Trump has proposed a $30 billion defense budget supplement which would take the base Pentagon budget for fiscal 2017 to $541 billion.

Milley said the Army’s basic training would stop by summer if Congress does not pass a budget and enters a full-year continuing resolution.

The Air Force’s General David Goldfein said units not actively preparing to go into conflicts could be grounded this summer.

For the Navy, a full-year continuing resolution would delay funding needed to complete delivery of several ships and prevent it from buying numerous new ships, Chief of Naval Operations Admiral John Richardson said, without specifying which ships.

The commandant of the Marine Corps, General Robert Neller,‎ said construction would be delayed on specialized amphibious warships that Marines use during operations.

In December, Huntington Ingalls Industries Inc. won a contract to design and build the USS Fort Lauderdale, an amphibious transport dock ship that would be used by the Marines.

Just before testimony began on Capitol Hill, an Air Force F-16 fighter jet crashed during a training mission just six miles (10 km) southwest of Washington’s Joint Base Andrews. The pilot ejected and suffered non-life-threatening injuries, the military said.

The crash was brought up by Goldfein as he expressed relief that the pilot was alright, but later during a discussion about the time and expense it takes to maintain the Air Force’s fleet of aircraft, which are on average 27 years old.

(Reporting by Mike Stone; Editing by Bill Trott)