MILWAUKEE -- Nationals' general manager Mike Rizzo was disciplined and catcher Ivan Rodriguez was fined for their roles in a dispute with umpires last week in New York, a Major League Baseball source said on Monday.

The league will not release the details of the discipline or the amount of the fine, the source said, confirming a story first reported by The Washington Post.

Umpire Phil Cuzzi called Jayson Werth out in a close play at first in the ninth inning of Thursday night's 1-0 loss to the New York Mets. Replays showed that Mets first baseman Daniel Murphy's foot came off the bag and that Werth was safe.

After the game, members of the Nationals' team argued with the umpires. Rizzo, who was unavailable for comment before Monday night's game at Milwaukee, said last week that the incident didn't have anything to do with the close play in the ninth inning.

The source said the league now considers the matter closed.

Strasburg takes first step toward return

MILWAUKEE -- Stephen Strasburg threw his first bullpen session on Monday since undergoing Tommy John surgery on his right elbow on Sept. 3.

"First bullpen in the books," Strasburg wrote on his Twitter account after throwing off a mound at the team's extended Spring Training facilities in Viera, Fla.

"Felt great!" Strasburg wrote. "Hopefully time will speed up now!"

Manager Jim Riggleman downplayed the significance of Strasburg's outing.

"That basically means he's on the slope instead of flat ground," Riggleman said. "It's probably 50 percent effort-wise. It's the next step in the rehab -- to get him throwing downhill, instead of on flat ground."

Strasburg, the No. 1 pick in the 2009 First-Year Player Draft, went 5-3 with a 2.91 ERA in 12 starts last year before being removed from a game at Philadelphia on Aug. 21, due to the elbow injury. The surgery to repair Strasburg's ulnar collateral ligament was performed by Dr. Lewis Yocum in Los Angeles.

There is an outside chance Strasburg could return to the Nationals this year. But it is more likely he would rejoin the club in 2012, if his rehab is successful.

Cardinals take back reliever Broderick

MILWAUKEE -- The St. Louis Cardinals on Monday took back reliever Brian Broderick, who had been selected by the Nationals in the Rule 5 Draft.

The Cardinals paid the Nationals $25,000 and assigned Broderick to Triple-A Memphis. The Nationals paid $50,000 to select Broderick during the Draft over the winter.

The right-hander was 0-1 with a 6.57 ERA in 11 games for the Nationals. The team designated him for assignment on May 14.

Ankiel plays in Eastern League game

MILWAUKEE -- Rick Ankiel went 0-for-4, striking out each time, for Harrisburg in a Monday night game on his rehab assignment.

Ankiel, on the disabled list with a sprained right wrist, batted leadoff in Double-A Harrisburg's 12-8 loss to Akron in an Eastern League contest.

Ankiel had been playing in extended Spring Training games at the team's facilities in Viera, Fla., before traveling to Akron for the game. With Adam LaRoche being placed on the disabled list on Monday to rest his ailing left shoulder, Ankiel could be activated before the Nationals' game with the Brewers on Tuesday.