The US plans to announce as soon as this week that it has purchased an advanced, medium-to-long range surface-to-air missile defense system for Ukraine.

A source familiar with the announcement has told CNN about this, Vigilant reports.

U.S. President Joe Biden announced recently that the U.S. would provide Ukraine with “more advanced rocket systems and munitions.”

In response to requests by Ukrainian forces, other military assistance is also likely to be announced this week, including additional artillery ammunition and counter-battery radars. Ukrainian officials have asked for the missile defense system, known as a NASAMS system, given the weapons can hit targets more than 160 km away, though the Ukrainian forces will likely need to be trained on the systems, a source said.

The US has been steadily announcing additional security assistance for Ukraine. Last week, the Biden administration announced an additional $450 million in military assistance for Ukraine, giving it four more multiple launch rocket systems and artillery ammunition for other systems.