Last month, the U.S. flags that fly over New York’s iconic Brooklyn Bridge suddenly turned white. Officials had no idea what they meant or who did it, even though the bridge is under constant surveillance. However, two German artists have claimed responsibility and say that there was nothing nefarious about their act.

Mischa Leinkauf and Matthias Wermke contacted The New York Times this week to clarify that they did not have terrorism in mind. In fact, what they were thinking about was far from it. They claimed to be celebrating “the beauty of public space” and the bridge itself. The bridge was designed by German engineer John Roebling and their act was on the 145th anniversary of his death.

The duo also gave the Times mysterious photos of white flags, noting that they have done similar stunts with little response.

“This was not an anti-American statement,” Wermke told the Times.

“From our Berlin background, we were a little surprised that it got the reaction it did,” Leinkauf added. “We really didn’t intend to embarrass the police.”

The two said that they did make the flags themselves, carrying them in backpacks up to the bridge. They also said that they made sure to use two white flags, honoring both Roebling and his son, Washington, who died on July 21, 1926. That’s why the hoax lasted from the night of July 21 into July 22.

However, the NYPD doesn’t think this is a closed case and the Manhattan DA’s office subpoenaed Twitter so they could find out who ran the @BikeLobby parody account. Whoever uses that handle claimed on July 22 that they changed the flags.

“We have some leads we’re following up on,” an NYPD spokesman told the Times. “The police commissioner feels optimistic that within a reasonable amount of time, we may be able to make some arrests.”