President Trump said at the White House Thursday that he would soon decide how the US would respond to the downing of a US drone by Iran.

“You will soon find out,” Trump said as he welcomed Canadian Prime Minister Justin Trudeau for a bilateral meeting. The two were expected to address reporters later.

Tensions have been mounting  over last week’s attacks on tankers near the Strait of Hormuz, assaults that Washington has blamed on Iran, which has denied the accusations.

Then, Iran’s Revolutionary Guard said Thursday it had shot down the RQ-4A Global Hawk drone over Iranian territory, while the US said the downing happened over international airspace in the Strait of Hormuz.

The US Central Command called it an “unprovoked attack” and Trump tweeted that “Iran made a very big mistake” in shooting it down.

White House officials huddled Thursday morning to discuss a response to Iran’s downing of the US Navy drone amid escalating tensions between the two countries.

The Defense Department announced Tuesday it would send 1,000 more troops to the region after the US said Tehran was involved in attacking two oil tankers in the Gulf of Oman last week.

The deployment is part of a defensive buildup by the US that included sending the USS Abraham Lincoln aircraft carrier strike group, B-52 bombers and Patriot anti-missile defenses to Qatar.