Crowdstrike noted a slowdown in Chinese hacking following the cybersecurity agreement Obama’s administration secured in 2015. But that now appears to have been reversed, the firm said in a report.

Adam Meyers, vice president of intelligence at Crowdstrike said: “By 2017 they started coming back and throughout 2018 they were back in full force. They have been very active and we expect to see that continue.”

The report comes as the Trump administration seeks to reach a trade deal with China, including provisions on intellectual property theft, ahead of a March 1 deadline. Trump has said he may extend that deadline and hold off on increasing tariffs on Chinese imports if there’s progress in the talks.

China’s hacking targets in 2018 included telecommunications systems in the US and Asia, according to Crowdstrike. Groups linked to Iran and Russia also appeared to target telecommunications, a sector that yields “the most bang for your buck” for hackers due to the large number of users that can be accessed after breaching a single network, Meyers said.

The findings align with concern in the U.S. about telecommunications security as the country transitions to the next generation of mobile networks and the Trump administration seeks to secure so-called 5G technology from foreign intelligence gathering. The administration has expressed particular concern about the spread of products made by the Chinese firm Huawei Technologies Co.

Crowdstrike said that Iran focused much of its cyber activity on Middle Eastern and North African countries while Russia engaged in intelligence collection and information operations worldwide. North Korea deployed hackers for financial gain and intelligence collection, while China targeted sectors including technology, manufacturing and hospitality, Meyers said.