The US military launched airstrikes and Iran retaliated Wednesday following the crash of an Army helicopter near the Strait of Hormuz that US President Donald Trump blamed on the Islamic Republic.

In a statement posted to social media, U.S. Central Command said the strikes would be “a proportional response to unjustified Iranian aggression.”

Two US helicopter crew members were rescued near Oman, but Trump’s decision to retaliate adds new strain to already fragile peace efforts.