Lobbyists scrambled to file paperwork after special counsel Robert Mueller indicted a pair of top Trump campaign officials with violating a rarely enforced federal law.
News reports began circulating earlier this year that Mueller and FBI agents were examining databases in the U.S. Justice Department's Foreign Agents Registration Unit, and an unusually high number of lobbyists filed paperwork disclosing their overseas work, reported NBC News.
Mueller indicted former Trump campaign manager Paul Manafort and his business partner Rick Gates in October on a variety of charges, including money laundering and failure to register as a foreign agent.
Previously, only three indictments had ever been handed up for alleged FARA violations since the amendment of the Foreign Agents Registration Act in 1966, although none resulted in a conviction.
An NBC News analysis found that first-time filings under FARA jumped 50 percent between 2016 and 2017, while the number of supplemental filings detailing campaign donations, meetings and phone calls doubled to 1,244 last year.
The parent company of Cambridge Analytica, a data firm owned by Trump donor Robert Mercer, recently filed paperwork showing it had helped spread propaganda against Qatar as part of an information war with Saudi Arabia and United Arab Emirates.
SCL Social Limited disclosed to the Justice Department that it had taken $333,000 from UAE to conduct a social media campaign linking Qatar to terrorism last year, as the Trump administration endorsed the Saudi and UAE positions and cut diplomatic ties with the tiny Gulf nation.
The company created multiple ads on Facebook, Twitter, YouTube and other social media with the hashtag #boycottqatar, which were spread during the United Nations General Assembly meeting in September.
Some of the ads called for President Donald Trump's attention to the issue, but the filing does not otherwise link the president or Cambridge Analytica to the activity.
Lobbyists say American firms have been doing business for foreign governments over the past decade to influence public opinion on humanitarian crises or introduce foreign leaders to U.S. officials.
One lobbyist told NBC News that U.S. firms can function as "little State Departments," and they were often reluctant to file under FARA because their foreign clients preferred to remain anonymous.
But Mueller's attention to FARA regulations has already pulled away some of that veil of secrecy, the network reported.