Major US metropolitan areas are taking extra measures to protect high-value assets and their civilians from revenge attacks following U.S. airstrikes in Iraq Friday that killed a top Iranian general.

New York City Mayor Bill de Blasio tweeted Thursday night that the New York City Police Department (NYPD) will take "immediate steps...protect key NYC locations from any attempt by Iran or its terrorist allies to retaliate against America. We will have to be vigilant against this threat for a long time to come."

Have spoken with Commissioner Shea + Dep Commissioner Miller about immediate steps NYPD will take to protect key NYC locations from any attempt by Iran or its terrorist allies to retaliate against America. We will have to be vigilant against this threat for a long time to come. — Mayor Bill de Blasio (@NYCMayor) January 3, 2020

De Blasio also tweet: "Worried for our city + our nation. Without the approval of Congress, the U.S. Government effectively declared war on Iran tonight. The American people had no say in the matter, despite voting time + again to stop endless wars + bring our troops home. This one will not end soon."

Worried for our city + our nation. Without the approval of Congress, the US Government effectively declared war on Iran tonight. The American people had no say in the matter, despite voting time + again to stop endless wars + bring our troops home. This one will not end soon. — Mayor Bill de Blasio (@NYCMayor) January 3, 2020

The Los Angeles Police Department (LAPD) tweeted early Friday and said, "the LAPD is monitoring the events developing in Iran. We will continue to communicate with state, local, federal, and international law enforcement partners regarding any significant intel that may develop."

While there is no credible threat to Los Angeles, the LAPD is monitoring the events developing in Iran. We will continue to communicate with state, local, federal and international law enforcement partners regarding any significant intel that may develop. — LAPD HQ (@LAPDHQ) January 3, 2020

On Thursday night, the Pentagon confirmed U.S. airstrikes killed Iran Quds Force commander Qasem Soleimani as well as six others at the Baghdad international airport.

"At the direction of the President, the U.S. military has taken decisive defensive action to protect U.S. personnel abroad by killing Qasem Soleimani, the head of the Iranian Revolutionary Guard Corps-Quds Force, a U.S.-designated Foreign Terrorist Organization," the Pentagon said in a statement.

Reports - An “American” drone strike just killed the #PMU’s “Head of Protocol,” Mohammed Reda al-Jabri, along with 2 aides & 3 “guests” (i.e. #IRGC) on their exit from #Baghdad Airport.



If that’s accurate, the #Trump admin just ratcheted up the ante in #Iraq in a big way. pic.twitter.com/p784XmVVq7 — Charles Lister (@Charles_Lister) January 2, 2020

House Speaker Nancy Pelosi requested the Trump administration brief lawmakers on the airstrike and what the plan of action was to mitigate any counterattacks in response to the killing of Soleimani.

"The Administration has conducted tonight's strikes in Iraq ... without the consultation of the Congress," Pelosi said in a statement. "The full Congress must be immediately briefed on this serious situation and on the next steps under consideration by the Administration, including the significant escalation of the deployment of additional troops to the region."

With New York and Los Angeles preparing for possible terrorist attacks in response to the killing of Soleimani, other major metro areas will likely follow suit. The world has entered uncharted waters on the third day of 2020. Anything - including a major attack on US soil - seems possible at the moment.