As the U.S. Defense Department seeks to again fly giant radar balloons from Aberdeen Proving Ground, two key Maryland lawmakers said Friday they oppose funding to resume the flights.

Sen. Barbara A. Mikulski said she had “grave reservations” about the safety of the balloons, and Rep. C.A. Dutch Ruppersberger said he also opposes the Defense Department's $27 million request to restart testing.

Last fall, one of the balloons of the Joint Land Attack Cruise Missile Defense Elevated Netted Sensor System — or JLENS — broke free of its moorings, drifting into Pennsylvania and dragging a cable behind it, knocking out power as it pulled down utility lines.

After the incident, the balloons were grounded, and lawmakers at the end of last year cut $30 million from the program's budget.

Last week, Defense officials submitted a request to Congress to shuffle money from other projects so they could get the balloons back on track — a move supported by Defense Secretary Ashton B. Carter.

Ruppersberger, whose district includes Aberdeen Proving Ground, said he opposes restarting the program.

“The JLENS failure jeopardized the safety of my constituents, and I can't, in good conscience, support its continuation in such a highly populated area,” said Ruppersberger, a Democrat.

The balloons were initially deployed at two sites at Aberbeen Proving Ground as part of a three-year test to see if they could effectively spot airborne threats.

Army investigators concluded that a series of mishaps led to the October snapping of the balloon's tether — which had been described as nearly unbreakable — after a system designed to account for changes in wind speed didn't work properly.

Another system designed to rapidly deflate the balloon if it did come free failed because it didn't have batteries installed, the Los Angeles Times reported.

“Bottom line, the investigation indicated a lack of training, supervision and oversight,” said Mikulski, also a Democrat. “I am really worried it could happen again.”

The football field-size balloon eventually came to ground in Moreland Township, Pa., where the military worked for several days to recover it.

The balloon was badly damaged during the incident, and officials said $4 million would be needed for repairs. Another $2.2 million would pay for measures to “prevent a similar incident,” according to the funding request.

In December, Army officials said they had received more than $300,000 in claims from people who say they suffered property damage from the balloon's errant flight.

At a Senate hearing Thursday, Adm. William E. Gortney, the head of the North American Aerospace Defense Command, said the system remains worthwhile at a time when the Russian military is demonstrating its cruise missile capability in Syria.

“It fills a capability gap that I do not have today,” Gortney said.

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