Defense officials discussed why the trilateral security partnership won’t be expanding under Pillar 1 any time soon — or maybe ever.

DIU, Australia’s Advanced Strategic Capabilities Accelerator and the United Kingdom’s Defence and Security Accelerator collectively launched this EW challenge in March as part of AUKUS Pillar 2.

Defense leaders from the U.S., U.K., and Australia are gathering in London on Thursday to participate in the trilateral security partnership’s ministerial meetings.

A U.S. defense official discussed progress and plans for Pillars 1 and 2 ahead of the meeting.

The U.S. Space Force will place one of three DARC radars at a repurposed army barracks in Pembrokeshire, Wales.

The AUKUS alliance is steering trilateral defense technology cooperation between Australia, the United Kingdom and the United States.

AUKUS is starting its prize challenge to identify electromagnetic spectrum technologies for offensive and defensive purposes, with winners slated to be chosen in July.

Companies from the U.S., U.K. and Australia will be eligible to compete.

Officials involved in the accelerator recently put out their inaugural “problem statement” call to industry.

The contract announced Tuesday supports the first part of a multiyear effort to “field-deploy and validate” miniaturized systems on military platforms, according to the company.