President Volodymyr Zelenskyy and some of Ukraine’s main European Union backers are weighing options to fill possible gaps after the Trump administration paused weapons shipments to his country.

Analysts say Ukraine’s European allies can fill some of the gaps and provide artillery systems. But they don’t possess alternatives to the U.S.-made HIMARS missiles and air defense systems, especially Patriots, which are crucial to help defend Ukrainian cities.

The United States said it would pause the delivery of some weapons to Ukraine as the Pentagon conducts a review of its munition stockpiles.