Apple and Samsung’s legal tussle over device patents escalated further this week when Apple filed a complaint with the U.S. International Trade Commission (ITC).

The iPhone maker asked the ITC to open an investigation into Samsung in response to a similar complaint recently filed by Samsung.

Samsung asked the ITC last week to block imports of Apple products into the United States, a standard move in patent complaints.

Apple’s full complaint was not yet available on the ITC’s website, but the company is likely to seek a similar injunction against Samsung’s products.

The ITC has not said whether it will investigate the tech giants’ claims. If the commission does decide to open an investigation into the complaints, it could take more than a year to complete.

Apple and Samsung are in the midst of an international legal battle that began in April when Apple alleged that Samsung’s Galaxy smartphones and tablet “slavishly copy” the iPhone and iPad.

Samsung proceeded to file a countersuit against Apple, sparking a series of complaints between the two companies that now spans the United States, South Korea, Tokyo, Japan and Manheim, Germany.