US President Donald Trump tours the border wall between the United States and Mexico in Calexico, California, April 5, 2019.

Wall Street strategists woke up Friday morning to a new front in the trade war. President Donald Trump announced late Thursday night that the U.S. will impose a 5% tariff on all Mexican imports beginning June 10.

The White House said it will increase the tariff in the coming months if Mexico doesn't take steps to control its border with the U.S.

Stocks opened down more than 300 points as strategists scrambled to assess the latest fallout and how best to advise clients.

"This is an escalation of trade wars and as such increases global uncertainty and lowers global trade and investment," Bank of America said.

This may also be a way for the White House to pressure Congress, according to strategists at Goldman Sachs.

"We view this as an attempt to show action on the immigration issue while also pressuring congressional Democrats to pass USMCA," they wrote.

One strategist predicted that the tariffs wouldn't last long but the damage may already be done.

"President Trump's latest trade bombshell — the threat to impose tariffs on Mexico if it does not stop the flow of illegal immigrants into the US — might turn out to be a short-lived threat that is quickly defused by commitments on border security, but it nonetheless looks damaging at a number of levels," Evercore ISI's Krishna Guha said.

Another analyst noted how things seemed to be on the right track as recently as last month but wondered whether any deal was even possible.

"As we've been arguing, these tweets have the potential to change the dynamics of global markets and it now seems like we could get a serious trade escalation that wasn't likely at the start of last month, especially as it had appeared Trump had looked like he wanted to get a deal done in 2019," Deutsche Bank said.

"The landscape has changed dramatically and it could be an interesting summer ahead."

Here is what the major strategists are saying: