A nighttime Russian missile strike on Odesa killed at least four people including a 16-year-old girl, regional authorities said Friday, in the latest in a series of attacks this week on the southern Ukrainian region that are likely intended to disrupt the country’s grain exports.

Four Russian missile and drone attacks on the Odesa region this week have killed 14 people and wounded around 20, according to local officials. The strikes have hit merchant ships and damaged port infrastructure in the region, which is a vital hub for Ukraine’s agricultural exports through the Black Sea.

An attack on Odesa late Wednesday killed nine people and hit a container ship sailing under the Panamanian flag — the third attack on a merchant vessel in four days, according to regional Gov. Oleh Kiper.

The apparent Russian effort to frustrate Ukraine’s exports, which bring vital revenue for a national economy battered by more than two years of war, coincided with a renewed push by Ukraine President Volodymyr Zelenskyy to ensure continuing military and financial support from his country’s Western partners.

Russia last year tore up an agreement that allowed Ukraine — one of the world’s biggest suppliers of grain and other food staples, especially to developing nations — to export produce safely through the Black Sea.

Months later, and amid successful Ukrainian attacks on Russia’s Black Sea fleet which forced its navy to back away from the coast, Ukraine established a shipping corridor that hugs the coast down to Turkey and opens a way to the Mediterranean Sea.